On Thu, 2013-03-07 at 14:57 +1100, Dave Chinner wrote: > On Wed, Mar 06, 2013 at 02:53:12PM +0100, Dennis Kaarsemaker wrote: > > On Fri, 2013-03-01 at 06:40 +1100, Dave Chinner wrote: > > > On Thu, Feb 28, 2013 at 03:12:16PM +0100, Dennis Kaarsemaker wrote: > > > > Hello XFS developers, > > > > > > > > I have a problem as described in the subject. If I read the xfs website > > > > correctly, this would be a place to ask for support with that problem. > > > > Before I spam you all with details, please confirm if this is true or > > > > direct me to a better place. Thanks! > > > > > > CentOS/RHEL problems can be triaged up to a point here. i.e. we will > > > make an effort to pinpoint the problem, but we give no guarantees > > > and we definitely can't fix it. If you want a btter triage guarantee > > > and to talk to someone who is able to fix the problem, you need to > > > work through the problem with your RHEL support contact. > > > > Hi Dave, > > > > Thanks for responding. We have filed support tickets with HP and Red Hat > > as well, I was trying to parallelize the search for an answer as the > > problem is really getting in the way here. So much so that I've offered > > a bottle of $favourite_drink on a serverfault question to the one who > > solves it, that offer applies here too :) > > > > > Either way: > > > > > > http://xfs.org/index.php/XFS_FAQ#Q:_What_information_should_I_include_when_reporting_a_problem.3F > > > > A summary of the problem is this: > > > > [root@bc290bprdb-01 ~]# collectl > > #<----CPU[HYPER]-----><----------Disks-----------><----------Network----------> > > #cpu sys inter ctxsw KBRead Reads KBWrit Writes KBIn PktIn KBOut PktOut > > 1 0 1636 4219 16 1 2336 313 184 195 12 133 > > 1 0 1654 2804 64 3 2919 432 391 352 20 208 > > > > [root@bc291bprdb-01 ~]# collectl > > #<----CPU[HYPER]-----><----------Disks-----------><----------Network----------> > > #cpu sys inter ctxsw KBRead Reads KBWrit Writes KBIn PktIn KBOut PktOut > > 1 0 2220 3691 332 13 39992 331 112 122 6 92 > > 0 0 1354 2708 0 0 39836 335 103 125 9 99 > > 0 0 1563 3023 120 6 44036 369 399 317 13 188 > > > > Notice the KBWrit difference. These are two identical hp gen 8 machines, > > doing the same thing (replicating the same mysql schema). The one > > writing ten times as many bytes in the same amount of transactions is > > running centos 6 (and was running rhel 6). > > So what is the problem? it is writing too much on the on the centos > 6 machine? Either way, this doesn't sound like a filesystem problem > - the size and amount of data writes is entirely determined by the > application. For performing the same amount of work (processing the same mysql transactions, the same amount of IO transactions resulting from them), the 'broken' case writes ten-ish times as many bytes. > > /dev/mapper/sysvm-mysqlVol /mysql/bp xfs rw,relatime,attr2,delaylog,allocsize=1024k,logbsize=256k,sunit=512,swidth=1536,noquota 0 0 > > What is the reason for using allocsize, sunit/swidth? Are you using > them on other machines? xfs autodetects them from the hpsa driver. They seem to be correct for the raid layout (256 strips, 3 drives per mirror pool) and I don't seem to be able to override them. > And if you remove the allocsize mount option, does the behaviour on > centos6.3 change? What happens if you set allocsize=4k? The allocsize parameter has no effect. It was put in place to correct a monitoring issue: due to mysql's access patterns, using the default large allocsize on rhel 6 makes our monitoring report the filesystem as much fuller than it actually is. > > xfs_info: > > > > [root@bc291bprdb-01 ~]# xfs_info /mysql/bp/ > > meta-data=/dev/mapper/sysvm-mysqlVol isize=256 agcount=16, agsize=4915136 blks > > = sectsz=512 attr=2 > > data = bsize=4096 blocks=78642176, imaxpct=25 > > = sunit=64 swidth=192 blks > > naming =version 2 bsize=4096 ascii-ci=0 > > log =internal bsize=4096 blocks=38400, version=2 > > = sectsz=512 sunit=64 blks, lazy-count=1 > > realtime =none extsz=4096 blocks=0, rtextents=0 > > > > > > And for reference, xfs_info on centos 5: > > > > [root@bc290bprdb-01 ~]# xfs_info /mysql/bp/ > > meta-data=/dev/sysvm/mysqlVol isize=256 agcount=22, agsize=4915200 blks > > = sectsz=512 attr=0 > > data = bsize=4096 blocks=104857600, imaxpct=25 > > = sunit=0 swidth=0 blks, unwritten=1 > > naming =version 2 bsize=4096 > > log =internal bsize=4096 blocks=32768, version=1 > > = sectsz=512 sunit=0 blks, lazy-count=0 > > realtime =none extsz=4096 blocks=0, rtextents=0 > > The only difference is that the centos 6 filesystem is configured > with sunit/swidth. That affects allocation alignment, but nothing > else. It won't affect IO sizes. > > > Linux 2.6.18-308.el5 (bc290bprdb-01.lhr4.prod.booking.com) 03/06/2013 > > > > Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await svctm %util > > cciss/c0d0 6.95 27.09 7.72 270.96 0.19 2.90 22.71 0.07 0.25 0.22 6.00 > > cciss/c0d0p1 0.00 0.00 0.00 0.00 0.00 0.00 47.62 0.00 1.69 1.61 0.00 > > cciss/c0d0p2 0.00 0.00 0.00 0.00 0.00 0.00 14.40 0.00 4.07 4.06 0.00 > > cciss/c0d0p3 6.94 27.09 7.72 270.96 0.19 2.90 22.71 0.07 0.25 0.22 6.00 > > dm-0 0.00 0.00 0.45 32.85 0.01 0.13 8.34 0.02 0.49 0.07 0.24 > > dm-1 0.00 0.00 6.97 264.13 0.15 2.77 22.10 0.07 0.24 0.22 5.93 > > So, 8k IOs on centos 5... > > > Linux 2.6.32-279.1.1.el6.x86_64 (bc291bprdb-01.lhr4.prod.booking.com) 03/06/2013 _x86_64_ (32 CPU) > > > > Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await svctm %util > > sda 0.00 3.60 6.00 374.40 0.06 44.18 238.17 0.11 0.28 0.16 6.08 > > dm-0 0.00 0.00 0.00 4.40 0.00 0.02 8.00 0.00 0.27 0.18 0.08 > > dm-1 0.00 0.00 6.00 373.20 0.06 44.11 238.56 0.11 0.28 0.16 6.04 > > And 128k IOs on centos 6. Unless there's a massive difference in > file layouts, nothing in the filesystem would cause such a > dramatic change in IO size or thoughput. I see, so now I need to find out what's causing the larger average request size. Would you happen to know a list of common causes? -- Dennis Kaarsemaker, Systems Architect Booking.com Herengracht 597, 1017 CE Amsterdam Tel external +31 (0) 20 715 3409 Tel internal (7207) 3409 _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
