LVM + RAID follow up

[richb at pioneer.ci.net (Rich Braun)]

"Derek Atkins" <warlord at MIT.EDU> responded to my query:
>> your swap is *not* configured as RAID?
>
> Yeah, that's how I have it configured.  It's much better performance
> to do it this way (why double the number of writes you have to make when
> you swap out a page?)..

Hmm...that statement doesn't compute.  The dual writes happen virtually
simultaneously, last time I did benchmarks the difference between non-RAID vs.
software RAID1 the write performance difference was something like 2%.

Is there something special about swapping versus filesystem access that would
cause a bigger performance difference?  Also--I tend to assume that swap
performance isn't particularly crucial anyway, because if I'm swapping that
means I need to upgrade system memory.  If overall system performance is
(virtually) unaffected, then it stands to reason that fault tolerance should
take priority.

Am I all wet, or do these observations hold true?

-rich


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