On Thu, Aug 29, 2013 at 08:08:25PM -0600, Chris Murphy wrote: > > On Aug 29, 2013, at 7:44 PM, Stan Hoeppner > <stan@xxxxxxxxxxxxxxxxx> wrote: > > > > More information would be helpful, specifically WRT the device > > stack underlying mkfs.xfs. I.e. we need to know more about the > > LVM configuration. > > > > See: > > > > http://xfs.org/index.php/XFS_FAQ#Q:_What_information_should_I_include_when_reporting_a_problem.3F > > Summary: laptop, one HDD, one 402GB partition is made into a PV, > one VG is created with that PV and is the only VG on the system, > one 400GB logical volume pool is created, one 100GB virtual sized > logical volume is created from the thin pool. .... > meta-data=/dev/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 > > Whereas if I mkfs.xfs on /dev/sda7, or if I create a regular LV > rather than a thinp volume, agcount is 4. It doesn't matter > whether I create the thinp with the chunk option set to default > (as above) or 1MB or 4MB. Which means that the thinp device has some difference in what it is telling mkfs.xfs about it's configuration that makes mkfs.xfs think it is a RAID volume, not a single disk. Basically, I think you'll find that the thinp device is emitting a an optimal IO size that is not aligned to the filesystem block size, so the AG count is being calculated as though it is a ~1TB "multidisk" device (which gives 16 AGs) and then setting sunit/swidth to zero because they aren't filesystem block aligned... Check the contents of /sys/block/<dev>/queue/{minimum,optimal}_io_size for the single device, the standard LV and the thinp device. I think that you'll find only the thinp device has a non-zero value. If the value from the thinp code is 512 (i.e. single sector) then that's a bug in the thinp device code as it should be zero... Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
