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Re: journal on an ssd



On Thu, Sep 11, 2008 at 03:07:01PM -0600, Andreas Dilger wrote:
> On Sep 11, 2008  07:43 +0200, Tobias Oetiker wrote:
> > Because if it is catastrophic, then it basically means that the
> > journal has to reside on a device that is as secure as to rest of
> > the data, meaning that if the data is on RAID6 then the journal
> > should be on RAID6 too.
> 
> No, because RAID6 is terribly sucky for performance.  If you need this
> kind of reliability triple-mirrored RAID 1 would be better.  Much less
> CPU overhead, and no extra IO.

RAID6 performs nicely for reads, but has quite bad performance for some
writes (non-sequential). Raid6 is actually surprisingly fast for
sequential reads.

Best regards
Keld


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