[HN Gopher] Windows on Btrfs
___________________________________________________________________
Windows on Btrfs
Author : susam
Score : 474 points
Date : 2023-04-21 21:08 UTC (1 days ago)
(HTM) web link (www.lilysthings.org)
(TXT) w3m dump (www.lilysthings.org)
| katherin_231 wrote:
| [dead]
| sebazzz wrote:
| If the BRTFS driver on Windows would implement setting ACLs I
| think that the Windows Store apps would work fine. The reason the
| probably fail is because those apps run within a Sandbox with
| limited permissions and need the right ACLs to run.
|
| You could then even hide all Linux directories of you wanted.
| qbasic_forever wrote:
| Haha wow that is so ridiculous it's awesome. Seeing both the
| Linux root and Windows root with Program Files living right next
| to usr, etc. is _wild_. Very cool hack!
| userbinator wrote:
| This is what we hoped WSL would be like, but it turned out
| very, _very_ different.
| PhilipRoman wrote:
| Can you elaborate? It seems to me that this is _exactly_ how
| WSL works. \\\wsl$\ <distro> provides access to the Linux
| filesystem
| jmmv wrote:
| WSL 1 was mostly like this, where Linux shared the file
| system with Windows, albeit in a subdirectory.
|
| WSL 2 is a completely different beast, with Linux storing
| its file system in a virtual disk image. \\\wsl$\ just
| gives you the illusion of being the same system, but that's
| just a networked file system.
|
| See https://jmmv.dev/2020/11/wsl-lost-potential.html
| eviks wrote:
| Yeah, very unfortunate they gave up :(
| chmod775 wrote:
| Given there's now native NTFS support in the Linux kernel, you
| could also do that that the other way around.
| flatiron wrote:
| I guess that paragon driver got merged. I remember the pull
| request...
| josephcsible wrote:
| I wonder which direction causes more breakage for the non-
| native OS.
| sebazzz wrote:
| I suppose you could store the chmod and group/owner in an
| NTFS alternative data stream, or reserve a special file on
| the file system that acts like the MFT.
| jwrallie wrote:
| I think getting around permissions would be an issue but
| when I was starting on Linux I remember there was a way to
| install to Fat32 inside a directory in parallel with
| Windows 95. The distro was called Phat, so the concept is
| not exactly new.
| watmough wrote:
| Yep, just posted about this. Late 90's right?
|
| I think it was Ygdrassil, or maybe a free distro off of a
| CD. Great investment of time as it got me into the
| oilfield doing tech support. Running Rocky 8 on a P1 Gen4
| now, so come a long way from my 486/Dx2.
| ur-whale wrote:
| To me, this article goes a very long way to demonstrate how
| screwed up people's thinking is in the windows users world.
|
| I mean, let's look at this objectively: the guy is amazed because
| he actually managed to boot windows off of a non MS-sanctioned
| software stack.
|
| There's nothing amazing here: these things should be the
| standard, and it pretty much is the case in the open-source
| world.
|
| And I certainly don't mean to diminish the technical achievement
| of the folks who stitched this together, quite the contrary, very
| nice feat.
|
| But what I'm trying to say: instead of being amazed because they
| managed to pull it off, they should be _demanding_ this kind of
| inter-operability between components of the steaming pile of
| shite that is windows in 2023.
| redder23 wrote:
| Btrfs still has no native encryption right? There is Dislocker
| that lets you open Windows partions encryption with Bitlocker. I
| switched from btrfs to zfs because Ubuntu has it naively
| integrated into the install. There was some issues about it
| recently about possible removal or some tools because badly
| maintained though.
|
| So if I want everything encrypted this is not helping me.
|
| Opening LUKS from Windows project is dead I think. But I am fine
| this way I basically have not booted up Windows up for gaming in
| months. And this one way sharing with Dislocker is enough for me.
| I think btrfs and zfs are rather a hasse on personal desktop
| systems, you just loose lots of space for snapshots you not
| really need, well I needed them on OpenSuse tumblweed because it
| was unstable but I since switched to Ubuntu LTS and I do not need
| them.
| KAMSPioneer wrote:
| If I recall correctly, the removal is the ZFS Event Daemon from
| Ubuntu, not ZFS itself.
|
| Which is pretty much fine; it was never finished anyway.
| Ambitious project with which Canonical seems to have bitten off
| more than it can chew...
|
| However a cursory search doesn't turn up any more info, so,
| grain of salt.
| biorach wrote:
| I highly recommend the Windows BTRFS driver.
| remram wrote:
| Recommend it for what?
| actionfromafar wrote:
| Compression and copy-on-write, perhaps.
| speed_spread wrote:
| Too bad the article doesn't talk about performance vs NTFS. Any
| quick and dirty comparative benchmark would have been nice. But
| then again, If BTRFS had been slower than NTFS it could have been
| due to a suboptimal (re)implementation.
| Rimintil wrote:
| This is due to file system filter [drivers], not the file
| system. NTFS is perfectly fine and performs well.
| dboreham wrote:
| Hmm. I thought the problem was that NTFS is not particularly
| fast at file creation. Generally not a problem, except for
| the folks who wrote the npm tooling which generates 10,000
| files in the blink of an eye.
| Rimintil wrote:
| Yep, I feel (a little) bad for anyone doing node
| development on Windows (though I probably should feel bad
| that they're having to dev in JS).
|
| But this isn't an "NTFS problem" as you'll have this occur
| on any filesystem that supports file system filters, like
| antivirus.
| brucethemoose2 wrote:
| I benchmarked both with a cross platform program. btrfs is
| massively slower on windows, especially with random IO (but
| also with sequential). Its even more disparate with compression
| turned on both.
|
| I cant remember the linux results... not that it matters, as I
| avoid NTFS writes on linux like the plague, even with the new
| kernel driver. Just this year, I tried trusting it _for a
| little while_ , and linux ntfs killed an entire backup HDD by
| corrupting the partition table :/.
|
| Mounting NTFS as read only is OK though.
| rbanffy wrote:
| I think nothing these days can perform worse than NTFS. I've
| been using Windows on my corporate issue laptop and anything
| that includes disk IO is a huge pain.
| ntauthority wrote:
| On Windows, I can enumerate a directory that accidentally got
| millions of files perfectly fine without the system itself
| breaking and with results being returned incrementally.
|
| On Linux/ext4, it takes an eternity for an enumeration to
| even start returning results and the entire OS gets stuck on
| IO while doing so.
| kitsunesoba wrote:
| Some amount of that might be coming from Windows Defender and
| similar, but yeah NTFS isn't exactly a speed demon.
| garaetjjte wrote:
| Nothing particularly wrong with NTFS, it's Windows
| filesystem architecture that is slow.
| solarkraft wrote:
| I can't find it right now, but I believe there was a talk
| from a Rust maintainer a while ago about the Rust
| installation being way slower than it should be, which
| was almost entirely a rant on Windows file system
| performance.
| ygra wrote:
| That one perhaps?
| https://www.youtube.com/watch?v=qbKGw8MQ0i8
|
| I don't recall it particularly ranty, though.
| solarkraft wrote:
| That's it, thank you!
|
| I chose the word because I remembered it being a bit
| rant-adjacent ("we're used to doing it this way, ... but
| windows does it that way"). But it's been a while since I
| watched it (not particularly attentively either, to be
| honest). That's just what stuck.
| overthrow wrote:
| I'd love to see a benchmark of NTFS on Windows vs NTFS on
| Linux. Unfortunately ntfs-3g uses FUSE so right now it's
| not really a fair comparison.
| mappu wrote:
| Linux has an upstream kernel driver for NTFS, you don't
| need fuse ntfs-3g any more (well, they have different
| quirks such as how UNIX permissions are emulated).
|
| The readwrite driver is new, but it always had an older
| readonly driver too, which would be fine for
| benchmarking.
|
| Back in 2011 Tuxera's proprietary Linux NTFS driver was
| maybe faster than ext as well:
| https://www.phoronix.com/news/OTU5Ng
| overthrow wrote:
| Thanks I wasn't aware of that, I stand corrected
| brucethemoose2 wrote:
| My laptop is a small Windows + Arch (f2fs) partitions + a big
| btrfs "cold storage" partition. Some notes:
|
| - "The btrfs driver for Windows is incredibly solid" is true...
| but (on NVMe) its also extremely slow. Like dramatically slower
| than NTFS, with or without compression.
|
| - You can share data, but writing with winbtrfs will screw up the
| permissions on linux unless you get the mount options _exactly_
| right.
|
| - Booting windows and ntfs conversion: there be dragons. The MS
| store isnt the only thing that breaks...
| KingLancelot wrote:
| [dead]
| Dwedit wrote:
| So how reliable is this and how long will it take before you get
| a badly corrupted disk?
| sneed_chucker wrote:
| Interesting. ReactOS has supported btrfs for a while, it's even
| an option when installing. Of course, ReactOS isn't really
| functional as of writing.
| c7DJTLrn wrote:
| Speaking of Windows storage drivers, years ago, I managed to get
| Windows to boot and run entirely in RAM using some fairly obscure
| tools from the reboot.pro forums. I always wanted to have an
| immutable Windows system that I could manage like cattle.
| Unfortunately, setting up such a system was extremely complicated
| and a manual process. I am aware that Windows now has a driver
| called UWF that functions a bit like an overlay filesystem and
| can create ephemeral overlays, but it's not quite the same as
| booting and running in RAM. It's also only available in
| Enterprise unless you enable it via registry edits.
| robotnikman wrote:
| UWF does come in handy for things like thin clients from my
| experience.
| ilyt wrote:
| I did that for lulz few times in Linux when I didn't wanted to
| fuck up with some old server's boot when I was decommissioning
| it.
|
| Just make a big file in /dev/shm, add it via loopback to LVM
| and migrate system partition on it, then run shred on drives
| without the annoying messages kernel screams when it has its
| storage destroyed underneath
| userbinator wrote:
| WinPE does that.
| bentcorner wrote:
| You can boot Windows off a VHDX, which might serve your same
| needs. I'm running like this right now - it has a few quirks
| but works pretty well.
| jaclaz wrote:
| JFYI, nowadays (if you have enough RAM) we have a good driver
| that can load Windows both as a Ramdisk and as Filedisk (using
| a VHD or RAW image) booting via grub4dos or grub4EFI, SVBUS:
|
| http://reboot.pro/index.php?showtopic=21787
|
| https://sourceforge.net/projects/svbus/
|
| http://mistyprojects.co.uk/documents/SVBus/index.htm
| nwellinghoff wrote:
| Awesome. Would love to see some performance marks.
| brucethemoose2 wrote:
| Its not good, see my above posts.
|
| But TBH its like this on linux too. BTRFS is a feature heavy
| CoW filesystem like ZFS, not a "light," intentionally low
| overhead fs like ext4 or f2fs (which is what I benched on
| linux).
| dmitrygr wrote:
| Nobody asked for this, wanted this, or imagined it. But it was
| done and it is epic! A tip of my hat!
| LukeShu wrote:
| I'm intending to write up some docs and announce it in the next
| few days, but since this thread is here, I might as well mention
| it now:
|
| On the topic of alternative btrfs implementations, I've been
| working on https://git.lukeshu.com/btrfs-progs-ng/ which is
| written entirely in Go.
|
| Its `btrfs-rec inspect mount --pv=/dev/whatever` is a read-only
| FUSE implementation of btrfs that is more fault-tolerant (of
| corrupt filesystems) than the normal in-kernel btrfs driver (and
| even more tolerant than `btrfs rescue` or `btrfs recover`).
|
| It's still missing a bit; RAID almost certainly doesn't work, and
| encryption is not implemented. But hopefully some folks will find
| it useful, or at least neat!
|
| Oh, comparison with the existing
| https://github.com/adam900710/btrfs-fuse : (1) Again, mine has
| better fault tolerance, (2) but mine is read-only, (3) mine
| supports xattrs (TODO in Adam's), (4) mine supports separate
| inode address spaces for subvolumes (Adam's doesn't due to
| limitations in FUSE, mine works around this by lazily setting up
| separate mountpoints for each subvolume).
| michaelmrose wrote:
| That is really neat have you considered contributing this to
| btrfs as a recovery option or putting out an ISO with this as a
| recovery tool?
| sm_1024 wrote:
| I wonder how hard it would be to replace FUSE with userspace
| block driver. That seems to be focused on performance.
|
| https://lwn.net/Articles/903855/
| kimixa wrote:
| Isn't that implementing a block device, so the level below
| the filesystem?
| Conan_Kudo wrote:
| > On the topic of alternative btrfs implementations, I've been
| working on https://git.lukeshu.com/btrfs-progs-ng/ which is
| written entirely in Go.
|
| Is this actually a blessed "next-generation" implementation? If
| not, could you please rename it so it doesn't confuse people?
| tadfisher wrote:
| If it's better, it should just be named btrfs-progs so folks
| get confused into installing superior tools.
| Thorrez wrote:
| > I forgot to take screenshots but it was the AMD stuff from the
| Microsoft Store failing to launch.
|
| What does AMD mean here? AMD the processor company? I don't see
| how that is related to changing the filesystem.
| mst wrote:
| I think it's the "from the Microsoft Store" part that's going
| wrong, and it just so happens the author noticed it on AMD-
| related store installed stuff.
| krylon wrote:
| GPU or chipset drivers, maybe?
| ThePowerOfFuet wrote:
| "Yeah, but your scientists were so preoccupied with whether or
| not they could, they didn't stop to think if they should." --Dr.
| Ian Malcolm
| pmarreck wrote:
| "Windows on ZFS" would be both far more impressive and horribly
| extend Windows' utility
| jasoneckert wrote:
| I've always thought filesystem compatibility between OSes should
| be a priority. Moreover, I've never understood why Microsoft
| developed ReFS instead of adopting ZFS.
| klodolph wrote:
| Yeah, so the semantics of the filesystem APIs on Windows is
| very different, so you're not going to easily port filesystem
| code to Windows from other operating systems. ZFS is CDDL and
| that won't fly on Linux. Linux filesystem code is GPL2 and that
| won't fly on macOS. Licensing is a bitch.
| overthrow wrote:
| Probably license issues - same reason Linus won't add ZFS to
| the linux kernel. https://itsfoss.com/linus-torvalds-zfs/
|
| If Linus is afraid of Oracle, MS should definitely be afraid
| lern_too_spel wrote:
| More likely Microsoft doesn't want its OS features to be
| controlled by a third party. The issues with using ZFS in
| Linux stem from the GPL. Neither Windows nor MacOS are
| affected.
| kitsunesoba wrote:
| Interesting, I would've expected more Windows software to just
| assume NTFS with some fallbacks for (ex)fat given how there
| haven't really been any other options for quite some time.
|
| How stable is Btrfs these days? Remember reading years ago that
| it was bad about spontaneously corrupting itself for no apparent
| reason.
|
| Curious if something similar is possible with ZFS.
| LukeShu wrote:
| IMO, it became stable somewhere between 2013 and 2016. I
| definitely haven't had any spontaneous corruption since at
| least 2016 (on multiple laptops and servers; btrfs volumes that
| mid-double-digit of terabytes)
|
| That said,
|
| - My BDB and SQLite databases tend to corrupt if my laptop
| battery dies and they're on a volume that's not on LUKS.
|
| - `btrfs check` (fsck), `btrfs rescue`, and `btrfs restore` are
| IMO not up to snuff if you do encounter corruption (caused by
| something else, like a failing drive). (But I'm working on that
| https://git.lukeshu.com/btrfs-progs-ng/ !)
|
| - `docker build` is weirdly slow on btrfs, I always set up a
| separate ext4 `/var/lib/docker` volume.
|
| - I do RAID and encryption separately in MD or LVM and LUKS, so
| no comments from me about the stability of btrfs' built-in RAID
| cor encryption.
| Slix wrote:
| > `docker build` is weirdly slow on btrfs, I always set up a
| separate ext4 `/var/lib/docker` volume.
|
| I'm currently doing this for a different reason. My docker
| builds started failing after some Ubuntu upgrade. I gave up
| and used ext4 for that docker directory to fix everything.
| https://serverfault.com/q/1127148
|
| It unsettled me because now I'm not sure whether btrfs (or
| docker with btrfs) is production-ready.
| LukeShu wrote:
| Docker has 8 different storage drivers that it can use...
| that's a lot, so you _know_ they don 't all get equal
| attention. As much as I love btrfs, it's probably fair to
| say that the only Docker storage driver that receives
| adequate attention to be production-ready is "overlay2".
|
| https://docs.docker.com/storage/storagedriver/select-
| storage...
| jdhendrickson wrote:
| Any ideas on what causes the docker issue? Or have you not
| poked it with a stick yet?
| LukeShu wrote:
| I haven't had a chance to dig in to it yet. Most of the
| time, Docker uses `overlayfs` to emulate COW, but on btrfs
| it can just use the filesystem's native COW. In my mind
| it's about equally likely that it's Docker's fault as it is
| btrfs's fault; that perhaps Docker's btrfs storage driver
| is doing something dumb.
|
| https://docs.docker.com/storage/storagedriver/select-
| storage...
| pxc wrote:
| For VMs and containers isn't it pretty common to use a
| subvol where CoW is disabled for their disk images? Same
| thing for ZFS with datasets that disabled CoW for things
| like that.
| curt15 wrote:
| > Same thing for ZFS with datasets that disabled CoW for
| things like that.
|
| Does ZFS let you disable CoW?
| pxc wrote:
| Huh. Looks like it doesn't! I knew that BTRFS did and saw
| that it was on the roadmap for bcachefs, and assumed it
| was something you could tweak in ZFS as well.
| yyyk wrote:
| Well, there's ReFS as well. That experience suggests there are
| issues that the author might come up against following boot:
| Case insensitive lookup (NTFS has the option for case sensitive
| subdirectories but that probably doesn't matter), Mark of the
| Web/SQL Server (Alternate data streams support), UWP/Microsoft
| Store apps support (IIRC requires FS encryption support via a
| specific interface), DLT (Object IDs), getting DISM to work for
| updates... It's cool to get this far, full support will
| probably need a bit more work.
| pxc wrote:
| There's a ZFS port for Windows but I don't think using it on
| the boot volume is supported. You could definitely try it,
| though!
| doublepg23 wrote:
| I enjoy it as ext4++. Would I trust it for RAID? Not
| particularly. There seems to be a decent amount of foot-guns
| still and I would greatly prefer just using ZFS.
|
| Granted, I do trust Synology using btrfs but they are also
| subject matter experts on the topic.
| ianlevesque wrote:
| Synology doesn't use btrfs in raid mode either. They put it
| on top of their LVM-based RAID instead.
| doublepg23 wrote:
| I thought I heard that as well but I had another person
| disagree so I'm not sure who is right.
| curt15 wrote:
| >How stable is Btrfs these days? Remember reading years ago
| that it was bad about spontaneously corrupting itself for no
| apparent reason.
|
| On one hand, Fedora and SUSE default to Btrfs. On the other
| hand, data corruption bugs are still being unearthed [1]:
|
| [1] https://bugzilla.redhat.com/show_bug.cgi?id=2169947.
| Arnavion wrote:
| FWIW I've been using btrfs for the root partition for a
| decade without any (observed) corruption problems. This is
| across multiple installs of OpenSUSE Tumbleweed on laptops
| and PCs, HDDs and SSDs and most recently an SD card. Back in
| the day it needed manual intervention to rebalance but that
| is automated now. Also, OpenSUSE's update program
| automatically takes pre- and post- snapshots, and these
| snapshots have saved me a lot of headache from botched
| upgrades.
| solarkraft wrote:
| Same here. Never had to do anything, with the notable
| exception of it being somewhat annoying to recover when the
| disk is full (which is why I've started to keep subvolumes
| that I can quickly delete).
|
| But I'm not running a RAID, which I believe is where almost
| all of the data corruption has happened.
| dontlaugh wrote:
| I've settled on unraid with btrfs partly for that reason.
| prmoustache wrote:
| I've had corruption on a btrfs root partition somewhere
| between last year and only this year.
|
| It was in files I wasn't really using anymore (some ssh key
| files on vps that weren't online anymore) so I have no idea
| when it really occured.
| nailer wrote:
| File systems are drivers and user space software shouldn't
| really see the difference.
| flatiron wrote:
| There is no way to have btrfs caps insensitive. So some
| software (poorly coded) could have capitalization issues that
| would not appear in NTFS that would in btrfs. But other than
| that I believe you are right (barring utilities specifically
| designed to interact with FS attributes)
| ElectricalUnion wrote:
| > There is no way to have btrfs caps insensitive.
|
| There is no way to make NTFS case insensitive either, it
| being case insensitive in Windows is a Windows
| implementation detail.
| nailer wrote:
| Does that mean windows could make any file system case
| insensitive?
| magicalhippo wrote:
| I've been running my Samba shares case sensitive for over a
| decade, only issue I've found is I can't rename "Foo" to
| "foo" without jumping through an extra hoop (add a letter
| or similar).
|
| Perhaps if I ran some software off it I might find some
| more issues but, overall quite little. The difference in
| speed is immense though.
| Dalewyn wrote:
| Synology apparently thinks btrfs is reliable enough to bet
| their credibility on it, for what that's worth.
| LanternLight83 wrote:
| It's really matured, and although the RAID5/6 Write Hole still
| exists, I wouldn't reccomend a ZDEV over RAID10 either, which
| is what I believe offers the best tradeoffs for most users on
| both filesystems. Love the flexibility that BTRFS provides via
| eg. the balance comand, and Snapper is great for snapshot
| management.
| skanga wrote:
| Can someone please explain the advantages of doing this?
| rbanffy wrote:
| It forces you to understand how Windows functions on unexpected
| conditions and that knowledge can be extrapolated to other
| situations where something on Windows fails for no apparent
| reason and you just know it because you saw it before.
|
| Do not underestimate the power of arcane knowledge.
| HeckFeck wrote:
| Step one: Include Linux kernel in Windows.
|
| Step two: Include Linux filesystem in Windows.
|
| Step three: Windows is Linux.
| viraptor wrote:
| We were already there in the past http://www.colinux.org/
| dgunay wrote:
| During my transition period from Windows to Linux, I stored the
| majority of my games on my NTFS drive because it was much
| bigger and I wanted them available on Windows in case they
| didn't work on Proton. I could play them from Linux with
| ntfs-3g but some of them would just refuse to launch unless I
| moved them a non-NTFS drive. Maybe they would've worked in this
| scenario? Hard to say.
| foobarqux wrote:
| Assuming subvolumes work you could dual boot and avoid having
| to partition your disk, which would allow you share the space
| on a drive freely between multiple OSes. That would be
| especially nice in places where drives and space are a premium,
| like a Steam Deck.
| xaduha wrote:
| This is a science experiment.
| solarkraft wrote:
| Less Microsoft-centric stuff on your computer.
|
| btrfs is pretty comfortable to manage, too.
|
| On that point: I wonder how the subvolume experience is.
| seiferteric wrote:
| Actually I have been looking for just this for several years,
| even as recently as a few weeks ago I was looking, but only
| found some commercial btrfs driver. The idea of unified storage
| is really nice, you don't have to decide how much each OS gets,
| and with btrfs you can just plop in another drive and extend
| onto it to transparently increase storage capacity. On top of
| that, tings like duplicating steam game assets would probably
| be a big win.
| csdvrx wrote:
| Why keep different filesystems outside of specific performance
| needs? I've experimented with weirder things, like Linux
| running on NTFS with the new kernel driver.
| yjftsjthsd-h wrote:
| > Linux running on NTFS with the new kernel driver.
|
| As the root file system? Does that work?
| csdvrx wrote:
| Well enough if you know what you're doing :)
|
| With posix perms, users and everything, there's no reason
| it shouldn't!
| dybber wrote:
| A performance comparison on simple file operations would be cool
| to see!
| brucethemoose2 wrote:
| See my above reply. Winbtrfs is massively slower on an NVMe
| drive... but still plenty usable.
| IronWolve wrote:
| I hate the new windows store container method of installing
| software. Its acts like an untouchable, unreadable, off limits
| container.
| userbinator wrote:
| It's good to see projects like this which basically confirm what
| we know about the modularity of the filesystem layer in Windows.
| In fact, the IFS API that enables this has been there since MS-
| DOS 4:
|
| https://en.m.wikipedia.org/wiki/Installable_File_System
|
| _Although I 'm sure that Windows would have some issues with
| that as XP was the last version that let you boot off of FAT32_
|
| I remember it being not too difficult to boot Vista and 7 from
| FAT32, although the official installer wouldn't let you.
| mise_en_place wrote:
| I was wondering about that too, specifically how ZwCreateFile
| and other file i/o functions would work. But if they're using a
| file system filter then it's not an issue. I'm curious where
| \\\Device and \\\DosDevices goes, considering Windows device
| files and their symlinks are there. I guess they just put them
| in under /?
| nly wrote:
| Linux supports a dozen filesystems and has FUSE for userspace.
|
| It's nice Windows can do things too though I guess.
| atoav wrote:
| I was running a dual boot system:
|
| - Linux on Btrfs
|
| - Windows on NTFS
|
| The Btrfs driver on windows allowed me to read and write Linux
| files from windows and the other way around. For my use cases
| this worked quite okay.
| solarkraft wrote:
| Pretty cool, apart from the fact that it's Windows you're
| booting.
|
| But what's up with UWP apps not working?
| ElectricalUnion wrote:
| The C:\Program Files\WindowsApps (or the equivalent
| X:\WindowsApps on other disks) needs some very specific ACL
| settings or the UWP sandbox will throw fits and refuse to
| start.
| paines wrote:
| Regardless of how cool this is, which I truly think, won't this
| "break" tons of apps and tools? NTFS and (V)FAT(32) arent't case
| sensitive and I have seen tons of projects which will fopen
| file.xy regardless if the file was created as File.xy or fIle.xy
| or FILE.xy.... (you get the picture).
| Kwpolska wrote:
| NTFS is case-sensitive internally and you can have case-
| sensitive files or directories. Back when WSL1 was the only
| version, I tried to compile some C++ stuff with MSVC. I ran
| `git clone` in WSL but cloned to the Windows partition. Visual
| Studio complained that EXAMPLE.H could not be found, even
| though it was there, except it looked like "example.h" in
| Explorer. (WSL2 does not use this feature, since cross-OS file
| access is done via network shares, and Linux files live in a
| virtual disk image.)
| EvanAnderson wrote:
| This is really cool and speaks to the modularity of the Windows
| file system stack. I love projects that customize Windows
| (working against its closed-source nature).
|
| There's an OpenZFS port to Windows[0]. I wonder if my hopes of
| having ZFS on Windows (including the boot drive, because I would
| love to be able to snapshot and rollback) would actually be
| possible.
|
| [0] https://github.com/openzfsonwindows/openzfs
| infogulch wrote:
| The author has refactored their branch with guidance and
| promoted their draft pr to open last month.
| https://github.com/openzfs/zfs/pull/14034
| lostmsu wrote:
| But Windows lets you snapshot and rollback via Volume Shadow
| Copying (System Restore in UI + 3rd party tool Shadow Explorer
| to browse snapshots).
| EvanAnderson wrote:
| Having used both VSS and ZFS fairly heavily I much prefer the
| ZFS experience. It seems more predictable and reliable in
| fulfilling its function.
|
| I am pretty strongly pro-Windows NT. I think there's a ton of
| good design and implementation in it. (The parts of NT that
| came from Win32 are the more irritating parts.)
|
| VSS isn't wholly unreasonable. The design seems pretty well
| thought-out. I particularly like the VSS providers that can
| interface with hardware-based snapshot mechanisms and VSS
| writers to allow software to quiesce IO. It's all pretty
| neat, but it seems to fail to take snapshots "mysteriously"
| pretty often in practice. Since I can't see the source I
| don't have much chance of actually figuring out what's going
| wrong either.
|
| I also like that VSS is clearly distinct from volume
| management and the filesystem itself. The layer violation
| inherent in the design of ZFS seems a bit clunky to me. In
| use, though, it has done very well for me and I haven't
| bumped up against limitations re: volume management and
| redundancy being tied to the filesystem too much (probably
| because I've always come at it with the expectation that my
| volumes are pretty much decided at deployment time and
| migration means starting a fresh zpool and starting over).
| javier2 wrote:
| I gave up on running windows because of the difficulty of sharing
| files with linux. So now I run only Linux. Some kind of native
| support for btrfs in windows would be great!
| AshamedCaptain wrote:
| I am sure this will break the second time you run Windows Update.
| ntauthority wrote:
| Unless it supports the transactional filesystem API, Windows
| Update won't even work in the first place. ReFS boot in fact is
| affected by the same issue at this time.
| krylon wrote:
| I thought that was deprecated since Windows Vista or 7.
| ntauthority wrote:
| It was introduced in Vista, deprecated for external use a
| bit later but the servicing system is still a heavy user of
| it.
| csdvrx wrote:
| > I am sure this will break the second time you run Windows
| Update.
|
| Then you are confidently wrong, because Windows Update rarely
| (if ever) touches the bootloader, while this is the main
| innovation of the WinBTRFS project.
| AshamedCaptain wrote:
| Until the day it touches it and replaces your selection from
| the UEFI firmware. Or repartitions the recovery partition. Or
| decides to move the recovery partition from the beginning of
| the disk to the end of the disk. All stuff I have personally
| seen Windows Update do.
|
| I am sure your custom bootloader will not be overwritten. All
| types of hell can happen, borking the entire installation --
| and your bootloader will still be perfectly fine.
| viraptor wrote:
| Windows update moving partitions around automatically? Have
| you got a reference for that?
| csdvrx wrote:
| There won't be any reference, as touching other OS
| partitions never happened for real.
|
| For the rest, there could be references, but it's just
| lingering legends now: yes, in the past, it could happen
| _BUT_ only for the Windows partitions (recovery 2700, efi
| EF00, msr 0701 c: 0700) and only if your partition was
| too small for a specific update. Then windows would do
| some careful resizing, in the worst case creating another
| partition out of its C: to avoid touching the rest. So it
| would 't break anything, just like how ntfsresize works
| on linux!
|
| For the selection from the UEFI, it was only if you used
| the default bootx64.efi and tried to repair the boot
| (windows detected this is not normal and would replace it
| by something to chainload bootmgfw.efi with)
|
| Anyway, since Windows 10 it doesn't happen, and I never
| had any problem at all with 11.
|
| Just use the recommended partition size (or more, I
| regularly make my EFI 4Gb), name your bootloader
| something else than bootx64.efi and it will be fine.
|
| The most windows might do is to reorder your UEFI boot
| entries (then go to settings and you can boot another
| system, same in recovery: just select your linux UKI or
| grub EFI)
| [deleted]
| AshamedCaptain wrote:
| https://www.tenforums.com/installation-
| upgrade/200367-window...
|
| https://superuser.com/questions/1210470/multiple-
| recovery-pa...
|
| https://www.reddit.com/r/sysadmin/comments/sbhd4g/thanks_
| mic...
| easton wrote:
| I wouldn't be so sure, Windows is famously annoying to goof
| with the boot loader on from a running install. You usually
| need to boot from another system to fix/reinstall it (at least,
| you did last time I needed to bring back the Windows bootloader
| on a borked dual boot).
|
| Although, since UWP doesn't work it's a moot point, that means
| you probably can't run Windows Update.
| heavyset_go wrote:
| This is insane and I love/hate it. Besides the MS Store stuff,
| which I try to avoid anyway as, in my experience, trying to
| launch them on Windows via SSH doesn't always work because of
| permissions, it's interesting as this opens up the ability to
| possibly dual boot windows from a subvolume without separate
| partitions/drives.
| issafram wrote:
| FYI you don't need Windows Store to install Terminal. You can
| download it from a browser as well
| nailer wrote:
| Whoa. So why didn't the Windows store work? Some kind of trusted
| environment thing?
| netsharc wrote:
| There are some hints in this document, like the OS needing to
| lock down installed app files:
|
| https://learn.microsoft.com/en-us/windows/msix/desktop/deskt...
|
| Or this issue: https://github.com/MicrosoftDocs/visualstudio-
| docs/issues/33...
| csdvrx wrote:
| In Linux terms, think about what would happen if you tried to
| use ACL (or fsattr or whatever non standard stuff) on a
| filesystem not supporting ACL: it would throw weird errors, and
| you may not properly handle them if you expected all
| filesystems to support ACLs.
| nailer wrote:
| User land generally doesn't care about file system specifics.
| Even in your ACL, example, opening a file would succeed or
| fail.
|
| I suspect this is much more likely to be a secure environment
| issue. Windows store wants to prevent piracy, there is no way
| the environment can be trusted because the boot loader wasn't
| signed by Microsoft, and therefore may be modified to help
| people pirate software.
| brucethemoose2 wrote:
| Even if you dont boot with btrfs, the store doesn't even
| recognize a btrfs partition as a valid drive for apps.
| levidos wrote:
| One life tip I've learned is that the Windwos Store's .msixbundle
| packages are just zip files that you can extract and usually will
| run fine.
|
| Change the .msixbundle extension to .zip, and open with 7-zip.
| Inside the archive, open & extract the appropriate .msix file for
| your architecture. Now you have Windows Terminal Portable. (I've
| done this with other apps too)
|
| To obtain a download link for a Windows Store package, you need
| to go to third party websites where you input the Windows Store
| URL, and it gives you the download link. Make sure the download
| link is from Microsoft domain.
|
| But in Windows Terminal's case, the bundle is published on their
| Github so you can download directly. If you want the Cascadia
| Code font, you need to install it manually by double clicking on
| the font from the package.
| 29athrowaway wrote:
| I/O in Windows XP is faster than Windows 11.
|
| 22 years of development for nothing.
| alliao wrote:
| nooo serious?
| mrb wrote:
| _" The btrfs driver for Windows is incredibly solid"_
|
| Hyperboles can be a fun writing style, but of course, it's not
| incredibly solid: https://github.com/maharmstone/btrfs/issues
| This is an exciting project though!
| einpoklum wrote:
| Title should be: Windows and Linux - btr(fs) together!
| rbanffy wrote:
| A more sensible approach would be to have a separate data volume
| to store important stuff on and leave it as BtrFS while letting
| Windows and Windows software run off NTFS.
|
| But, then, what'd be the fun of having a computer you don't need
| to fix?
| apatheticonion wrote:
| Related tangent: Something I don't fully understand (perhaps I
| just haven't found a project that facilitates it) is why there
| isn't a Windows extension (driver?) that allows for native
| mounting of ext4 partitions within Windows explorer.
|
| Surely, given the Linux native file system is open source, adding
| the ability to mount ext4 partitions natively should be something
| people can add to Windows?
|
| I have seen third party applications with custom file explorers
| that can open ext4 partitions (in the same way you open a 7zip
| file) and I also understand you can mount linux partitions via
| WSL to access them via explorer - I would just love it if there
| was a way to natively mount ext4 in the Windows shell.
|
| Up until now I have been using NTFS as my "universal" format -
| for drives shared between Windows, Linux and MacOS. I think exfat
| has recently gained support in all three platforms but it's not
| reliable for an internal hard drive (I think?).
| p_l wrote:
| There used to be an ext2 driver for NT, I think opensource
| even, but there simply had not been enough interest to keep it
| updated or built for newer versions
| hackmiester wrote:
| > I think exfat has recently gained support in all three
| platforms but it's not reliable for an internal hard drive (I
| think?).
|
| I've been doing this for a few years now. It just doesn't
| support some stuff, like permissions, but for just a pile of
| files, it's fine.
| toastal wrote:
| No symlinks, no transparent compression... there's quite a
| few mission things
| toastal wrote:
| Missing*
| dale_glass wrote:
| > Related tangent: Something I don't fully understand (perhaps
| I just haven't found a project that facilitates it) is why
| there isn't a Windows extension (driver?) that allows for
| native mounting of ext4 partitions within Windows explorer.
|
| Such projects have long existed, but I suspect there's a lack
| of interest.
|
| It's a difficult technical problem with a narrow usage niche.
| You need somebody who wants both Windows and Linux, and wants
| to use the same physical disks. Today, why bother? You can use
| a NAS, cloud storage, virtualization, etc.
| Spivak wrote:
| Or just using NTFS since Linux now has good support for it.
| leoc wrote:
| Wanting to dual-boot sometimes isn't _that_ rare, surely. And
| local storage for documents remains popular too. It seems to
| reflect the reality that serious Linux development effort has
| been very server-focussed for a long time.
| HyperSane wrote:
| Why would I dual boot when I could use a VM?
| mmerlin wrote:
| For performance, to use the entire RAM and CPU of the
| bare metal machine
| HyperSane wrote:
| For what?
| nly wrote:
| The overhead of VMs, properly provisioned, is minimal
| these days. Even going with card passthrough just works.
| circuit10 wrote:
| That doesn't work if you have one GPU (unless you shut
| down the Linux desktop which defeats the point)
| mtrower wrote:
| You need a whole damn extra card for passthrough. With
| the price of today's high end cards, that option seems...
| less than attractive.
| rezonant wrote:
| Let alone trying to _fit_ 2 3-slot GPUs in your machine,
| or have enough PCIe lanes to take advantage of them
| checkyoursudo wrote:
| Single GPU passthrough:
| https://github.com/joeknock90/Single-GPU-Passthrough
| pjmlp wrote:
| For me dual boot has ended the day VMWare and Virtual Box
| became good enough, that was around 2010.
| csomar wrote:
| Sure but the Linux audience is certainly not one that pays
| for such things. Like the Parent Poster explained, this is
| a hard and niche technical problem. Someone has to foot the
| bill for this, and apparently there is a "need" for it but
| no market to sell it.
| whitemary wrote:
| The Linux audience is software engineers and the
| companies they who employ them.
| cpach wrote:
| So why haven't such an open source application
| materialized after all these years?
| voltagex_ wrote:
| Well you'd need to fund the cost of a kernel driver
| signing certificate and get it through WHQL as well.
| That's just for a start. So this wouldn't be something
| you could build yourself.
| circuit10 wrote:
| Surely you'd just need to turn driver signing off
| KyeRussell wrote:
| Back when I was a desktop Linux user, a very sizeable
| portion of the other people I knew that used it weren't
| "software engineers". They were 'power users'. I don't
| think that my experience was all that atypical.
| csomar wrote:
| The need is more personal than corporate.
| smoldesu wrote:
| There are corporate solutions (like the Paragon drivers),
| they just suck. Paragon tried merging this code into the
| Linux kernel, but the code was so bad and unmaintainable
| that it was rejected. The FOSS solution is using FUSE,
| but that requires a UNIX-like OS for easy porting. Unless
| Windows ditches the NT kernel altogether, I don't think
| you can expect native filesystem extensions beyond NFS
| support.
|
| GNU philosophy is not about moneymaking or footing the
| bill. Sometimes a problem gets worse when you throw money
| at it.
| Kwpolska wrote:
| Linux has good NTFS drivers. If you want to dual boot and
| share files, you just make three partitions: Windows
| (NTFS), Linux (whatever the cool kids are using these
| days), and Shared Data (NTFS).
| wongarsu wrote:
| And before linux had good NTFS drivers, you just put your
| shared data on FAT32.
| joveian wrote:
| EXFAT is another option these days.
| KyeRussell wrote:
| I mean...using desktop Linux in the first place is already
| an incredibly harsh qualifier. macOS and even Windows (+
| WSL) are no doubt serving the needs of many people that
| need a *nix environment for their work, and eating into the
| percentage of people that would otherwise push for Linux to
| be supported by their employer, or use it at home. That and
| the ubiquity of containerised workloads.
|
| It's really not outside the realm of reason for the subset
| of those people that want to use Windows for something
| other than playing video games is small enough for there to
| not be the base level of interest needed for this stuff to
| get off the ground.
| prmoustache wrote:
| On the contrary I have the feeling dual boot is a thing of
| the late 90's-early 2000's when processors didn't come
| equiped with virtualization extensions and virtualization
| was slow as hell.
|
| Having to reboot is so inconvenient, sooner or later ina
| dual boot setup you leave your non-preferred env colecting
| dusts and cobwebs.
| dale_glass wrote:
| These days probably quite rare, except for gaming.
| Virtualization is far more convenient.
| sgtnoodle wrote:
| Valve is working hard to change that.
| itsboring wrote:
| Used to dual boot, but with the combo of steam/proton and
| VFIO passthrough + looking glass, it's been really solid
| to just run both at the same time. File sharing between
| the two is pretty easy in that case, because it's just
| the usual rsync/scp tools or SMB share.
|
| Although, I've found I very rarely need the guest for
| gaming anymore, more so for opening the odd Photoshop
| file and similar tasks.
| checkyoursudo wrote:
| This is where I am at now.
|
| In 2010, used to dual boot. In 2014 or so, I switched to
| VFIO GPU/SSD passthrough and never booted to Windows
| again. In maybe 2019 or so, I pretty much stopped using
| passthrough even, though this is partly because I stopped
| playing a few games that proton didn't run (mostly
| because of e.g. Easy Anti Cheat, etc).
|
| I don't even have my windows ssd installed in my tower
| any more, that's how little I expect to need it these
| days.
| kaetemi wrote:
| Yeah, if you're going to exclude the common use cases,
| obviously it's going to be rare. (:
|
| People still use local storage.
|
| (I'd also like native ext4 support in Windows.)
| dale_glass wrote:
| Yeah, but when I boot Windows for gaming, I don't care
| about sharing data with Linux.
|
| And given the availability of cloud storage, I can just
| upload whatever little I need to share.
| mst wrote:
| Not all dual boot systems are "main OS" plus "wintendo."
| Quite a lot of the ones I encounter on personal machines
| are, certainly, but people doing actual dev stuff on both
| is still a use case.
| circuit10 wrote:
| Virtualisation is really laggy if you have no GPU
| acceleration, there are ways to get it working but they
| either need two GPUs or are still slower than native
| NegativeLatency wrote:
| When I dual booted a hackintosh and windows (2015) I did so
| on 2 different drives so I wouldn't have windows scribbling
| over my boot sector
| watmough wrote:
| Back in the day, and I mean like mid-late 90's, you could
| actually install the Linux kernel, files etc., straight onto
| a Windows FAT partition and boot into it.
|
| Not exactly what was being asked for, but a weird old fact
| I'd forgotten about.
| arprocter wrote:
| Reminds me of Wubi - I had a Pentium 4 box with a BIOS
| password that wouldn't clear, and this let me turn it into
| something 'useful'
| progman32 wrote:
| There was a distribution called WinLinux that did this,
| iirc. Installed like a normal piece of windows software.
| Was my first foray into unices when I was a young kid.
| There were some fun games in that distro!
| fdr wrote:
| Sometime in the early 2000s, when microarchitectural
| features for virtualization were rare, I used coLinux in a
| working capacity. It has a design was amazing at how well
| it worked given the constrained size of the code changes.
| In short, it ran a copy of Linux in supervisor mode _in
| addition to_ Windows (this is the "driver mode"). At the
| same time. Both in supervisor mode. As a giant coroutines
| yielding to one another.
|
| https://en.wikipedia.org/wiki/Cooperative_Linux
| http://www.colinux.org/publications/Reprint-Aloni-
| OLS2004.pd...
| lta wrote:
| A friend of mine has been using this setup for a very
| long time do be able to write music and work on the same
| station. I remember I was amazed at how solid the thing
| was.
|
| Does anyone know if there's a relationship between
| colinux and how ms eventually ended up implementing wsl ?
| mst wrote:
| I was really quite fond of colinux, out of assorted VM
| tech, colinux, cygwin and WSL1 and 2 that have provided
| me with enough of an X11+xterm+ssh rig to get work done
| comfortably on a windows machine I think colinux and WSL1
| have been the least friction overall.
| yellowapple wrote:
| The niche surely ain't _that_ narrow, especially as Linux-
| based devices like Raspberry Pis and Steam Decks grow in
| popularity; being able to ready EXT-formatted SD cards and
| such seems like it 'd be valuable even from Windows.
| lasftew wrote:
| It might be convenient, but it is also more complex than just
| being able to read file systems. External disks or partitions
| containing data in particular will / should always be fully
| encrypted nowadays, so you'd need interoperability of disk
| encryption schemes as well (dmcrypt, bitlocker). NAS can
| handle that transparently.
| hyperdimension wrote:
| To your last point: try UFS! I use it for cross-platform flash
| drives. Better than FAT32, anyway.
| cpach wrote:
| I guess you're referring to Universal Flash Storage rather
| than Unix File System? (:
| SSLy wrote:
| Maybe UDF?
| hyperdimension wrote:
| Yeah, UDF. UFS won't get you terribly far with cross-
| platform support... Thank you.
| efrecon wrote:
| Probably. Last time I check UDF is a format supported by
| the 3 major OSes out of the box.
| yyyk wrote:
| I recall getting UDF cross compatibility required a bit
| of non-trivial work[0], did this improve recently?
|
| [0] https://github.com/JElchison/format-udf
| tinus_hn wrote:
| Writing filesystem drivers for Windows is extraordinarily
| difficult, more so than generic drivers and the result is hard
| to call GPL compatible because a signature which is basically
| not obtainable for individuals is required to load them.
| pseudostem wrote:
| I installed Debian on WSL for the very first time a few weeks
| back. Windows explorer gives access to the Debian folder
| _while_ it is running and no access otherwise. Had me
| scratching my head. I don 't know much about virtualisation,
| but if that is the key, they could probably have a highly
| customised, small Linux kernel running all the time perhaps.
| cobertos wrote:
| WSL uses the 9P protocol for filesystem stuff[1]. There's a
| 9P server running in Debian and a 9P client running in
| Windows to connect it together
|
| [1]: https://en.m.wikipedia.org/wiki/9P_(protocol)#Server_app
| lica...
| csdvrx wrote:
| > I think exfat has recently gained support in all three
| platforms but it's not reliable for an internal hard drive (I
| think?).
|
| It's not, and recovery tools are still lacking. Keep using NTFS
| for now.
| JonathonW wrote:
| exfat's reliability "issues" are by design-- it's not
| journaled, to simplify implementation (and reduce resource
| use) on embedded devices and reduce wear on flash media.
|
| It's not a replacement for NTFS in applications where it's
| already being used (large disks, anything where important
| data is being stored). Rather, it's a modernized replacement
| for FAT32 for things like camera memory cards, eliminating
| some of FAT32's limitations (like the file size limit) while
| remaining similarly lightweight.
| bramblerose wrote:
| ext2fsd and ext2ifs do exactly that, although neither of them
| is very actively maintained (but do they really need to?)
| themoonisachees wrote:
| I've used ext2fsd in the past and it worked well. I don't
| think you could boot windows off of it but you can certainly
| start touching your Linux drive from there.
| bstar77 wrote:
| It's entirely due to Microsoft's hubris.
| KyeRussell wrote:
| Yeah. Screw Microsoft for not supporting a file system with a
| rounding error desktop user base.
| aruggirello wrote:
| Microsoft didn't support ext because too few people were
| using it to justify the effort, yet somehow they went to
| great lengths and implemented the whole WSL, and... ~twice
| at that - for a possibly smaller user base?
| pajko wrote:
| Maybe you are looking for https://www.paragon-
| software.com/home/linuxfs-windows/
| viraptor wrote:
| Paragon has been doing it for quite a while. You just need to
| pay extra. https://www.paragon-software.com/business/extfs-for-
| windows/
| gfody wrote:
| contact Sales for a quote. I guess the price depends on how
| many files you plan on storing?
| smw wrote:
| $20 if you're a home user?
| chronogram wrote:
| That's the business page, the home user page shows EUR19,95
| for me.
| mukesh610 wrote:
| Don't use this. I once tried it and it changed the UUID of
| the Linux partition without any warning. Grub was unable to
| pick up the partition and boot, so I was stuck at grub
| rescue.
|
| God knows what other bugs their software has.
| throwaway894345 wrote:
| Pretty sure there isn't an ext4 spec, it's just the reference
| implementation. Microsoft could build something that is
| compatible, but keeping compatibility as the reference
| implementation changes may not be straightforward.
| haileys wrote:
| The counterpoint to this is that ext4 can't change
| dramatically enough to cause problems without breaking
| compatibility with older kernels or older filesystems.
| yellowapple wrote:
| Certain features (like case-insensitivity) already do break
| compatibility, as I found out the hard way trying to get
| GRUB to boot from an ext4 filesystem with said features
| enabled.
| mekster wrote:
| When could ext4's specification change?
|
| It's not just the MS implementation that might break but
| everybody's file system may be in danger.
|
| Filesystem is supposed to be as backward compatible as it
| should be.
| aaronmdjones wrote:
| Ext4 was explicitly designed with maintaining backwards and
| (limited) forwards compatibility in mind precisely for the
| reason pointed out in my sibling comments.
|
| Depending on the filesystem features you enable, you can even
| mount an ext4 filesystem with the ext2 kernel driver, and you
| can already mount an ext2 or ext3 filesystem with the ext4
| kernel driver.
|
| A large part of this compatibility is due to the bitmap of
| compatible, compatible read-only, and incompatible filesystem
| flags in the filesystem superblock.
|
| For example, when ext4 got support for extents, that's an
| incompatible feature; you cannot mount an ext4 filesystem
| with extents with the ext3 kernel driver. This does not even
| require ext3 to know what an extent is because it's just
| indicated as an unknown (from the ext3 driver's perspective)
| incompatibility flag.
|
| On the other hand, the implementation of sparse superblocks
| (keeping fewer copies of the superblock around to allow for
| more blocks to be used for file data on filesystems intended
| to house lots of large files) is merely a read-only
| compatibility bit; you can mount an ext4 filesystem using
| sparse superblocks with an ext2/ext3/ext4 driver that does
| not support them, in a read-only manner. This cannot be
| mounted read-write because the implementation may try to
| place a filesystem superblock where file data is supposed to
| be, which would lead to at best wasted space (negating the
| feature) or at worst limited filesystem corruption.
|
| When feature changes that could break things are made to the
| ext4 implementation in the Linux kernel, they are always done
| so using these (in)compatibility flags, ensuring that only
| implementations that can entirely support the feature can
| mount them read-write, and that implementations whose ability
| to read would not be affected can still mount them read-only.
| This allows you to create future filesystems (using e.g.
| mke2fs(8)) and not turn those features on while doing so, if
| you want the filesystem to be used by other implementations.
| Something you already have to bear in mind if you're creating
| a filesystem using a modern mke2fs but intended to be read by
| ancient Linux kernels.
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