On Sat, Jul 16, 2016 at 09:07:25AM +1000, Dave Chinner wrote: > On Fri, Jul 15, 2016 at 11:46:47AM +0200, Carlos Maiolino wrote: > > On Thu, Jul 14, 2016 at 10:19:02PM +0200, Marcin Sura wrote: > > > Hi, > > > When I create filesystem I can specify su and sw paramteres which match > > > underlying storage device. > > > So for example, If I have raid 6 volume made of 6 + 2 disks with stripe > > > size of 256k I create xfs with: > > > mkfs.xfs -d su=256k,sw=6 <disk> > > > But what if I will extend original volume by 2 disks. sw will 8. Will > > > be there a performance panelty compared to filesystem created from > > > scratch with correct sw parameter? > > > BR > > > Marcin > > > > Complementing Dave's answer, you can also mount the filesystem with new > > alignment configuration. > > > > You can use: sunit=value and swidth=value for mounting the FS with the new > > settings. man xfs for more info. > > That doesn't change the fact that everything that already existed in > the filesystem would now be misaligned and hence have performance > issues on read and/or overwrite. Only newly written data will be > aligned to the new stripe width. > > Also, keep in mind that stripw width cahnges are an alignment change > you generally canot make through the mount options. Static metadata > such as allocation group headers are laid out according to the > physical geometry of the filesystem, and that cannot be changed. > hence the mount options can only change the stripe unit/width when > they don't change the alignment constraints. e.g. doubling of the > stripe width will work because the alignemtn of the stripe units is > still the same. However, changing from 6 disks to 8 won't work > because it is a different physical alignment... > Thanks for the detailed info, it was my bad to have not predicted such details > Cheers, > > Dave. > -- > Dave Chinner > david@xxxxxxxxxxxxx > > _______________________________________________ > xfs mailing list > xfs@xxxxxxxxxxx > http://oss.sgi.com/mailman/listinfo/xfs -- Carlos _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
