Post API3zbVs4WMnf3iQRU by 1ace@mastodon.gamedev.place
 (DIR) More posts by 1ace@mastodon.gamedev.place
 (DIR) Post #AMtRoDEDbPVwdQxWN6 by craftyguy@freeradical.zone
       2022-08-25T17:29:40Z
       
       0 likes, 0 repeats
       
       things they don't tell you in the mdadm manpage, #36:it's apparently a really bad idea to create a mdraid device using unpartitioned disks (e.g. '/dev/sda' instead of '/dev/sda1')
       
 (DIR) Post #AMtpa3x3h6agi2ibi4 by martijnbraam@fosstodon.org
       2022-08-25T21:56:02Z
       
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       @craftyguy I haven't had any issues with doing exactly this
       
 (DIR) Post #AMu8CxsE1YZIKN9oIq by kinetix@mycrowd.ca
       2022-08-25T19:50:10.149498Z
       
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       @craftyguy Why is it a bad idea?
       
 (DIR) Post #AMu8CyNm8FnzuDv0To by craftyguy@freeradical.zone
       2022-08-26T01:24:47Z
       
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       @kinetix I guess some motherboards take the liberty of writing to disks that they think are unpartitioned. or at least that's what I can gather happened... I moved an array to a new system (with a supermicro board), and suddenly the array was corrupted/unrecoverable. consensus on the internets suggest that this can happen sometimes 🤷also see: https://www.phoronix.com/news/Linux-Software-RAID-ASRock
       
 (DIR) Post #AMu9p7FzgXrOO71xsO by craftyguy@freeradical.zone
       2022-08-26T01:42:54Z
       
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       @kinetix so I actually just found something... the UEFI spec says that a backup GPT table is used if the main one is corrupt (it would appear to be if the whole disk was part of an array...)(section 5.3.2 here[1])So my best guess for what happened is the firmware on the new Supermicro board saw a corrupt GPT, used what it thought was the backup & really screwed things up.Could have been avoided by using an array of partitions instead (which has other benefits too)1. http://www.uefi.org/sites/default/files/resources/UEFI%20Spec%202_7_A%20Sept%206.pdf
       
 (DIR) Post #AMuARAbrfU1zn4PEye by craftyguy@freeradical.zone
       2022-08-26T01:49:46Z
       
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       @kinetix there are also some other benefits to using an array of partitions, since you can control their size... which is super handy if you try to use or replace a disk from a different manufacturer (e.g. a 4TB Seagate drive is not exactly the same size as a 4TB WD drive)
       
 (DIR) Post #AMuiJalTw9jb2ASjrs by tyil@fedi.tyil.nl
       2022-08-26T08:09:18.256Z
       
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       @martijnbraam@fosstodon.org @craftyguy@freeradical.zone Yeah me neither, I pretty much always raided entire disks together when I used mdadm.
       
 (DIR) Post #API3zbVs4WMnf3iQRU by 1ace@mastodon.gamedev.place
       2022-11-05T10:14:48Z
       
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       @craftyguy why? I do that all the time (with luks or lvm) and never had any issues; what problem did you encounter?