[Gllug] Re: RAID on laptop or xfs?

[Bruce Richardson]

On Fri, Apr 01, 2005 at 01:33:44AM +0100, Liam wrote:
> 
> I'm not sure how much hdd corruption you will suffer if you are using
> a journalling file system when the drive loses power, all changes to
> files being stored in the journal.

Except that they will not all be there if some of the changes were in
the writeback cache, that's the whole problem.  What makes it worse is
that these drives do not usually flush the data blocks from the cache to
the disk in the same order that they were written to it.  This can make
complete nonsense of a journal or mean that only random portions of a
RAID stripe were written to disk at poweroff.

> 
> If some of that cache is for reads (i.e. not stuff waiting to be
> written) than you can ignore that for data corruption purposes.

It's called a writeback cache.

-- 
Bruce

Explota!: miles de lemmings no pueden estar equivocados.
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