Re: Advanced Linux Kernel/Enterprise Linux Kernel

From: Pavel Machek (pavel@suse.cz)
Date: Mon Nov 20 2000 - 08:34:23 EST


Hi!

> > > Actually, I was planning on doing on putting in a hack to do something
> > > like that: calculate a checksum after every buffer data update and check
> > > it after write completion, to make sure nothing scribbled in the buffer
> > > in the interim. This would also pick up some bad memory problems.
> >
> > You might want to take look to a patch with crc loop option.
> >
> > It does verify during read, not during write; but that's even better because
> > that way you pick up problems in IO subsystem, too.
>
> You would have to store the checksums on the filesystem then, or use a

I store checksums in separate partition.

> verify-after-write. What I was talking about is a
> verify-the-buffer-didn't get scribbled. I'd then trust the hardware to
> report a write failure. Note that if something scribbles on your buffer
> between the time you put good data on it and when it gets transfered to
> disk, you can verify perfectly and still have a hosed filesystem.

Actually, I have 50% chance detecting that corruption. If it happens
between application and loop, I detect nothing. If it happens between
loop and disk, I catch it.
                                                                Pavel

-- 
Philips Velo 1: 1"x4"x8", 300gram, 60, 12MB, 40bogomips, linux, mutt,
details at http://atrey.karlin.mff.cuni.cz/~pavel/velo/index.html.

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