On 10/30/2014 02:50 PM, Brian Foster wrote: > On Thu, Oct 30, 2014 at 02:15:16PM -0500, Stan Hoeppner wrote: >> On 10/30/2014 06:46 AM, Brian Foster wrote: >>> On Wed, Oct 29, 2014 at 04:38:22PM -0500, Stan Hoeppner wrote: >>>> On 10/29/2014 01:47 PM, Eric Sandeen wrote: >>>>> On 10/29/14 1:37 PM, Brian Foster wrote: >>>>>> On Tue, Oct 28, 2014 at 12:35:29PM -0500, Eric Sandeen wrote: >>>>>>> Today, this geometry: >>>>>>> >>>>>>> # modprobe scsi_debug opt_blks=2048 dev_size_mb=2048 >>>>>>> # blockdev --getpbsz --getss --getiomin --getioopt /dev/sdd >>>>>>> 512 >>>>>>> 512 >>>>>>> 512 >>>>>>> 1048576 >>>>>>> >>>>>>> will result in a warning at mkfs time, like this: >>>>>>> >>>>>>> # mkfs.xfs -f -d su=64k,sw=12 -l su=64k /dev/sdd >>>>>>> mkfs.xfs: Specified data stripe width 1536 is not the same as the volume stripe width 2048 >>>>>>> >>>>>>> because our geometry discovery thinks it looks like a >>>>>>> valid striping setup which the commandline is overriding. >>>>>>> However, a stripe unit of 512 really isn't indicative of >>>>>>> a proper stripe geometry. >>>>>>> >>>>>> >>>>>> So the assumption is that the storage reports a non-physical block size >>>>>> for minimum and optimal I/O sizes for geometry detection. There was a >>>>>> real world scenario of this, right? Any idea of the configuration >>>>>> details (e.g., raid layout) that resulted in an increased optimal I/O >>>>>> size but not minimum I/O size? >>>>> >>>>> Stan? :) >>>> >>>> Yeah, it was pretty much what you pasted sans the log su, and it was a >>>> device-mapper device: >>>> >>>> # mkfs.xfs -d su=64k,sw=12 /dev/dm-0 >>>> >>> >>> What kind of device is dm-0? I use linear devices regularly and I don't >>> see any special optimal I/O size reported: >> >> It's a dm-multipath device. I pasted details up thread. Here, again: >> > > Oh, I see. So this is just getting passed up from the lower level scsi > devices. On a quick look, this data appears to come from the device via > the "block limits VPD." Apparently that should be accessible via > something like this (0xb0 from sd_read_block_limits()): > > # sg_inq --page=0xb0 /dev/sdx > > ... but I don't have a device around that likes that command. It would > be interesting to know what makes the underlying device set optimal I/O > size as such, but that's just curiosity at this point. :) The device isn't setting it. It's global. Any LUN of any RAID level reports the same parms. So apparently it's hard coded in the firmware. I informed our field engineer at the vendor of this issue, and the fact it prompted a patch to XFS, but haven't received a response. An educated guess is that they want to see 1 MiB IOs entering the controller regardless of the stripe geometry of the back end LUN. Could be lots of reasons for this, valid or not. However, given it advertises a minimum optimal IO size of 512 bytes this seems counterintuitive. Thanks, Stan > Brian > >> # multipath -ll >> 3600c0ff0003630917954075401000000 dm-0 Tek,DH6554 >> size=44T features='0' hwhandler='0' wp=rw >> |-+- policy='round-robin 0' prio=50 status=active >> | `- 9:0:0:3 sdj 8:144 active ready running >> `-+- policy='round-robin 0' prio=10 status=enabled >> `- 1:0:0:3 sdf 8:80 active ready running >> >> >> # blockdev --getpbsz --getss --getiomin --getioopt /dev/dm-0 >> 512 >> 512 >> 512 >> 1048576 >> >> # blockdev --getpbsz --getss --getiomin --getioopt /dev/sdj >> 512 >> 512 >> 512 >> 1048576 >> >> # blockdev --getpbsz --getss --getiomin --getioopt /dev/sdf >> 512 >> 512 >> 512 >> 1048576 >> >> >> >> Cheers, >> Stan >> > > _______________________________________________ > xfs mailing list > xfs@xxxxxxxxxxx > http://oss.sgi.com/mailman/listinfo/xfs > _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
