On 8/29/13 1:09 AM, Chris Murphy wrote: > > Is it expected when formatting, using defaults, that a thinp volume > compared to either a conventional LV or partition of the same size, > should have a higher agcount? woohoo, thinp testing! :) > > HDD, GPT partitioned, 100GB partition size: > > [root@f19s ~]# mkfs.xfs /dev/sda7 > meta-data=/dev/sda7 isize=256 agcount=4, agsize=6553600 blks > = sectsz=512 attr=2, projid32bit=0 > data = bsize=4096 blocks=26214400, imaxpct=25 > = sunit=0 swidth=0 blks > naming =version 2 bsize=4096 ascii-ci=0 > log =internal log bsize=4096 blocks=12800, version=2 > = sectsz=512 sunit=0 blks, lazy-count=1 > realtime =none extsz=4096 blocks=0, rtextents=0 > > > A 400GB partition, made into PV, PV added to VG, and all extents put into a thinpool volume, a 100GB virtual sized LV: > > [root@f19s ~]# mkfs.xfs /dev/mapper/vg1-data > meta-data=/dev/mapper/vg1-data isize=256 agcount=16, agsize=1638400 blks > = sectsz=512 attr=2, projid32bit=0 > data = bsize=4096 blocks=26214400, imaxpct=25 > = sunit=0 swidth=0 blks > naming =version 2 bsize=4096 ascii-ci=0 > log =internal log bsize=4096 blocks=12800, version=2 > = sectsz=512 sunit=0 blks, lazy-count=1 > realtime =none extsz=4096 blocks=0, rtextents=0 > > > > I get agcount=4 on a conventional LV as well. Why agcount=16 on thinp? Hm. calc_default_ag_geometry() in mkfs does this stuff. There is a "multidisk" mode which creates more AGs, but you don't have any stripe geometry set, which is what is supposed to trigger it. What does # blockdev --getiomin --getioopt mkfs.xfs /dev/mapper/vg1-data say? I'm guessing we picked multidisk mode due to what looks like stripe geometry, but then maybe it was out of bounds, and we turned it back off. Or something... that does seem likely though, because on the same sized fs created on a file: w/o stripe geometry we get 4 ags: $ mkfs.xfs -dfile,name=testfile,size=107374182400 meta-data=testfile isize=256 agcount=4, agsize=6553600 blks ... w/ stripe geometry we get 16 ags: $ mkfs.xfs -dfile,name=testfile,size=107374182400,su=64k,sw=4 meta-data=testfile isize=256 agcount=16, agsize=1638384 blks ... so at the time we calculated AGs, we thought we had stripe geometry, and then eventually discarded it. -Eric _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
