On Wed, Jul 18, 2007 at 01:51:16PM +0100, Robin Hill wrote:
> Just to pick up on this one (as I'm about to reformat my array as XFS) -
> does this actually work with a hardware controller? Is there any
> assurance that the XFS stripes align with the hardware RAID stripes? Or
> could you just end up offsetting everything so that every 128k chunk on
> the XFS side of things fits half-and-half into two hardware raid chunks
> (especially if the array has been partitioned)?
If you partition the device and does not explicitely align the
partitions on a stripe boundary then you'll get that effect. Also if you
do not use partitions but use LVM instead, then the stripe size should
be a power of 2 meaning the number of data disks should also be a power
of 2 to get the best performance.
> In which case would
> it be better (performance-wise) to provide the su,sw values or not?
Only testing can tell... But if one logical file system block spans
multiple stripes then you will lose some performance; if that will be
noticable or not depends on your usage pattern.
Gabor
--
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MTA SZTAKI Computer and Automation Research Institute
Hungarian Academy of Sciences
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