On Dienstag, 20. Juli 2010 Andrew Debenham wrote: > I'm am new to XFS and am in the process of trying to tune an XFS file > system. I spent some time searching through this mailing list's > archives but wasn't able to find anything that matched the question > that I have (I apologize in advance if this issue has already been > addressed). Thanks for reminding me, wanted to write a FAQ entry, done now: http://xfs.org/index.php/XFS_FAQ#Q:_How_to_calculate_the_correct_sunit.2Cswidth_values_for_optimal_performance > I have a 3ware 9650SE-12M installed and have a RAID6 unit with 11 x > 1.82 TB SATA drives and stripe size of 256KB. I found an earlier > thread that discussed calculating the values for sunit and swidth > for RAID5, which stated that the swidth would be "sunit x (# disks > in stripe - 1)". So, finally the question - would the swidth for a > RAID6 volume be "sunit x (# disks in stripe -2)? > > If that is the case, then here is what I would expect my values to > be: sunit = 512 > swidth = 4608 I think sunit should be as big as the RAID controllers stripe size, as it describes the smallest I/O XFS should do. So sunit=512 would make it possible that XFS writes a single sector, while the RAID controller needs to read/write 256KB with your stripe size, resulting in performance degradation. But I'm no XFS dev, so maybe wait for a clearing from someone who has deeper XFS knowledge than me. sunit=262144 swidth=9 Would be my suggestion for your setup. -- mit freundlichen Grüssen, Michael Monnerie, Ing. BSc it-management Internet Services http://proteger.at [gesprochen: Prot-e-schee] Tel: 0660 / 415 65 31 ****** Aktuelles Radiointerview! ****** http://www.it-podcast.at/aktuelle-sendung.html // Wir haben im Moment zwei Häuser zu verkaufen: // http://zmi.at/langegg/ // http://zmi.at/haus2009/
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