By: iz (i.delete@this.z.com), March 16, 2021 1:25 am
Room: Moderated Discussions
Anon (no.delete@this.spam.com) on March 15, 2021 9:05 am wrote:
> iz (i.delete@this.z.com) on March 15, 2021 8:10 am wrote:
> > Temporary functionality loss is to be expected, but other than that I would expect software to
> > be able to recover from unexpected crashes without problems.
> You mean, you expect software to crash too and then restart? Because I don't think many software
> is build expecting a device driver or OS service crash when waiting for an IO operation.

No, I expect that if the software is restarted in any way (automatically or manually), that it starts up and functions again, instead of getting stuck or crashing again.

I'm purely talking about software unexpectedly ending and being restarted itself, not cascading failures or device drivers or OS services crashing.

> > Considering how often unexpected
> > power failures happen I don't think people accept crap software that can't recover from that.
> And that's why we use UPS.

The failure rate of UPSs is surprisingly high and most people don't use them anyway. The point is not that you can't protect against power loss failure, the point is that even software that never crashes needs to be able to handle sudden exits.

> Even if the software can recover from a crash it may require some time, database software may
> take a long time to recover.

Yes, assuming it does recover automatically (hurray for DBs in VMs with lying host systems).

If that's unwanted and the software has to be up "immediately", it becomes more critical software than non-critical and my advice would be not to use such database software to begin with, or use distributed versions that can handle individual node failures.

> But this case I don't know if is a good candidate for this discussion
> since this class of softwares may benefit from by-passing OS services, what do you think?

I don't think databases should write their own disk drivers. But I do think database software is a good example where microkernels don't help much, as database software is also one huge blob of unsafe code, just like kernels.

Databases also deal with lots of persistent state, so they are hard to restart in a clean way anyway, just like file systems. But because both deal with persistent state, they have to be able to cleanly restart, otherwise they're useless.
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TopicPosted ByDate
x86 - why unite when you can fragment?anonymou52021/03/12 06:16 PM
  x86 - why unite when you can fragment?Linus Torvalds2021/03/13 01:18 PM
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      x86 - why unite when you can fragment?Jon Masters2021/03/13 07:44 PM
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        x86 - why unite when you can fragment?anonymou52021/03/14 05:31 PM
          x86 - why unite when you can fragment?anon22021/03/14 08:07 PM
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                    Microkernel?Anon2021/03/15 09:05 AM
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                          Microkernel?iz2021/03/16 08:36 AM
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                                Microkernel?dmcq2021/03/18 06:30 AM
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                                    Microkernel?---2021/03/18 09:49 AM
                                    Microkernel?dmcq2021/03/18 10:59 AM
                                      Microkernel?dmcq2021/03/18 04:09 PM
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                            Microkernel?---2021/03/20 08:35 AM
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                Microkernel?dmcq2021/03/15 11:51 AM
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                    Microkernel?dmcq2021/03/16 09:17 AM
                      Microkernel?Jukka Larja2021/03/16 11:22 AM
                        Microkernel?dmcq2021/03/16 04:06 PM
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                    Already did (NT)Foo_2021/03/17 02:55 AM
                      Already didanon22021/03/17 03:46 AM
                        Already didEtienne Lorrain2021/03/18 02:31 AM
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              Microkernel?dmcq2021/03/16 08:40 AM
        x86 - why unite when you can fragment?Konrad Schwarz2021/03/17 10:19 AM
    x86 - why unite when you can fragment?anonon2021/03/15 07:37 AM
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