[HN Gopher] Redundant Against What?
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Redundant Against What?
Author : r4um
Score : 24 points
Date : 2021-04-15 06:53 UTC (16 hours ago)
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| tkinom wrote:
| I have designed/coded two redundant systems before.
|
| First one is super complex redundant router done by 100+
| engineers. All TCP states, BGP states, complete configurations
| were replicated to backup CPU. If the primary failed, power off,
| etc, the standby will take over, etc. When the failed unit comes
| backup, it become the new stanby. Demo works fine, but the
| company sold just 1 system for $200K. The company did sold for
| four hundred millions. It paid off my mortgage.
|
| 2nd is relatively simple done by me in 3 weeks including testing,
| etc. It is a system convert 48 channels digital MPEG streams to
| analog NTSC signals for analog cable plant such as Comcast.
| Xilinx power PC running linux. All configurations were sync. Auto
| switch over on power off, network disconnect, etc. The system can
| detect all failure conditions in 50 milliseconds. Very cool to
| demo - if you blink your eye and you will miss the system failure
| over event. Support in service SW upgrade - update backup to new
| SW, sync config over, force switch the primary and update the new
| backup to new SW with ZERO downtime.
|
| The product was very successful - only one firmware bug found
| after two years in the field. Sold $100 millions+ to various
| cable companies. But the VC air drop a "professional CEO" and
| "scale" the company from 16 people to 300+ people. Did two more
| rounds and manage to burn the company to the ground and sold it
| for pennies.
|
| Redundant system design are not that hard and can be simple. It
| is best to remember KISS - "Keep It Simple Stupid".
| smiley1437 wrote:
| I was called in to troubleshoot system once, a small 2-node
| cluster with a SAN with no single point of failure in the fabric.
|
| They had both their 1500va UPSs plugged into a single 15amp
| circuit.
| zabzonk wrote:
| I once found an electric kettle plugged into a UPS.
| cyberlab wrote:
| I like the word _antifragile_ instead of redundancy. I don 't
| operate a datacenter, but in my own personal computing space, I
| try to build antifragile systems that can bounce back from
| failure rather rapidly. It is astonishing for example, just how
| many times I have to roll back a Windows 10 install because it
| likes to randomly break for whatever reason. It could be
| anything: a faulty update that corrupts the whole OS. The hard-
| drive gets filled up really quickly when doing gaming video
| captures, or games that do really heavy writes to the SSD and
| wearing it out within a year of use.
|
| Currently I use virtual machines to mitigate this, and you need a
| beefy setup to do this. If a virtual machines fails, I have a
| 'template' virtual disk image where I can start afresh. One
| caveat to VMs is you can't do gaming since you're emulating an
| OS, so when I can I use a bare metal solution for gaming. You can
| do basic gaming for games that use low resources (like
| Minecraft). But forget about playing Crysis or other monsters in
| a VM!
| yjftsjthsd-h wrote:
| I'm actually surprised by this; I was under the impression that
| CPU only took a ~5-10% hit and you can pass the GPU directly to
| a VM. So I've never actually done it, but I expected VMs to be
| fine for gaming these days. Where does it fall apart?
| cyberlab wrote:
| VMs are fine for basic games like Minecraft (that isn't
| resource intensive). It falls apart when you play anything
| that is resource intensive. Even if you have, say, 32GB of
| RAM and a good CPU+Graphics, the fact you have to emulate
| anything at all means it gets _noticeably_ laggier. You can
| laud the fact that the GPU gets passed to the VM, but since
| we are emulating, you _will_ notice that.
| throwaway3699 wrote:
| VMs aren't emulating anything. Services like Stadia and
| GeForce Now explicitly rely on virtualizing gaming machines
| to be able to scale them. Nvidia even have a technology for
| slicing and dicing up large graphic cards to multiple
| client VMs.
| nitrogen wrote:
| A service that is basically a one way video conference
| call with a remote system isn't exactly a benchmark for
| high performance/low latency gaming.
| cwyers wrote:
| Xbox One/Series X/S actually runs games within a VM as
| well:
|
| https://wccftech.com/xbox-one-architecture-explained-
| runs-wi...
| smnrchrds wrote:
| Why not _robust_?
| cyberlab wrote:
| 'Robust' assumes the system doesn't need to bounce back from
| failure, since it's strong enough. But most systems these
| days are not so strong that they can deal with anything. We
| have to resort to hacks and mitigation strategies like
| _snapshotting_ (in the case of VMs) or using fault tolerant
| filesystems like ZFS or RAID if you operate a datacenter.
| BiteCode_dev wrote:
| Antifragile, at least by the definition of Taleb that I
| believed coined the term, is not "bouncing back quickly", but
| actually improving after the event.
|
| I don't see how a computing system could be anti-fragile. A
| team building one, certainly, learning from each mistake and
| improving the system.
|
| But a system by itself, baring some miraculous learning AI, I
| don't see how.
| heavenlyblue wrote:
| An anti fragile computing system is a deep learning algorithm
| because it gets better from fluctuations in data as it forced
| it to generalise than end up in local minima
| blacktriangle wrote:
| I realize I'm nitpicking, but that's not what antifragile means
| at all. I think the word for what you are describing is
| resilient.
|
| Antifragile systems are those which don't just continue to
| function in the face of unknown inputs, but in fact perform
| better in the face of shocks to the system. A classic example
| of this is the California redwood forests that thrive in the
| face of regular forest fires.
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