Re: ide write cache issue? [Re: Something corrupts raid5 disks slightly during reboot]

Andre Hedrick
2003-11-02T06:06:15Z

I added the flush code to flush a drive in several places but it got
pulled and munged.

The original model was to flush each time a device was closed, when any
partition mount point was released, and called by notifier.

In a minimal partition count of 1, you had at least two flush before
shutdown or reboot.

So it was not the code because I fixed it, but then again I am retiring
from formal maintainership.

Cheers,

Andre Hedrick
LAD Storage Consulting Group

On Sat, 1 Nov 2003, Ville Herva wrote:

> On Sat, Nov 01, 2003 at 08:01:14PM +0100, you [Willy Tarreau] wrote:
> > On Sat, Nov 01, 2003 at 08:25:18PM +0200, Ville Herva wrote:
> >
> > > Is there anything special in booting to DOS instead of different linux
> > > kernel, other than that it would rule out some strange kernel bug that is
> > > present in 2.2 and 2.4?
> >
> > No, it was just to quicky confirm or deny the fact that it's the kernel
> > which causes the problem. It could have been a long standing bug in the IDE
> > or partition code, and which is present in several kernels.
>
> I vaguely recall some ide write cache flushing code was fixed some time ago,
> but I can't find it in the archives. Maybe I dreamed that up. But I still
> wonder why an otherwise idle drive would hold the data in write cache for so
> long (several minutes.)
>
> > But as you say that it affects two different controllers, there's little
> > chance that it's caused by anything except linux itself.
>
> Unless the drive is buggy wrt. flushing its write cache. But I think it's
> a quite distant possibility.
>
> > Then, the reboot on DOS will only tell you if the drives were corrupted at
> > startup or at shutdown.
>
> Yep. I'll try to find the moment to boot the beast into something else than
> the current kernel / distro (it could in theory be something in userspace,
> though I cannot think what).
>
> > > BTW: the corruption happens on warm reboots (running reboot command), not
> > > just on power off / on.
> >
> > OK, but the BIOS scans your disks even during warm reboots.
>
> True, I mainly made this note because I hadn't mentioned it before in the
> thread, and I thought it might have some relevance wrt. possible ide write
> caching problems. I didn't mean it as a response to the BIOS theory.
>
>
> -- v --
>
> v@iki.fi
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