[mythtv-users] XFS RAID Tweaking

[Matthew McClement]

On 10/21/2010 07:13 PM, Rob Dege wrote:
> Hello,
> 
> I just stumbled upon this wiki entry today regarding XFS tweaks, and
> have a question about the RAID Array section
> (http://www.mythtv.org/wiki/Optimizing_Performance#Optimizing_XFS_on_RAID_Arrays)
> 
> My system currently uses 2 disks in software raid 0 for /myth.  The
> filesystem was built/formatted back in 2007 (when I first built the
> machine).  Given that I don't want to reformat the partition, is it okay
> to add the custom sunit and swidth values to the mount options, even
> though they wouldn't match the values on the partition?
> 
> xfs_info on /dev/md0 shows the sunit=16 and swidth=32
> 
> The script recommends sunit=128 and swidth=256

The settings can be changed at mount time without regardless of what was
used during the initial mkfs.xfs. The only thing that might still be
badly aligned is the journal, but there's not much you can do about that
without reformatting. And I second the suggestion to use allocsize to
help reduce fragmentation.

Matt