On Fri, Aug 19, 2011 at 1:04 AM, Jonathan Barber <jonathan.barber@xxxxxxxxx> wrote: > On 18 August 2011 18:41, Paras pradhan <pradhanparas@xxxxxxxxx> wrote: >> On Thu, Aug 18, 2011 at 10:13 AM, Jonathan Barber >> <jonathan.barber@xxxxxxxxx> wrote: >>> >>> On 13 August 2011 04:24, Paras pradhan <pradhanparas@xxxxxxxxx> wrote: >>> > Alan, >>> > Its a FC SAN. > > [snip] > >>> > If I don't make an entire LUN a PV, I think I would then need partitions. Am >>> > i right? and you think this will reduce the speed penalty? > > [snip] > >>> You can also just not use any partitions/LVM and write the filesystem >>> directly to the block device... But I'd just stick with using LVM. >>> >> >> >> Here is what I have noticed though I should have done few more tests. >> iozone o/p with partitions (test size is 100MB) >> - >> "Output is in Kbytes/sec" >> " Initial write " 265074.94 >> " Rewrite " 909962.61 >> " Read " 1872247.78 >> " Re-read " 1905471.81 >> " Reverse Read " 1316265.03 >> " Stride read " 1448626.44 >> " Random read " 1119532.25 >> " Mixed workload " 922532.31 >> " Random write " 749795.80 >> -- >> >> without partitions: >> "Output is in Kbytes/sec" >> " Initial write " 376417.97 >> " Rewrite " 870409.73 >> " Read " 1953878.50 >> " Re-read " 1984553.84 >> " Reverse Read " 1353943.00 >> " Stride read " 1469878.76 >> " Random read " 1432870.66 >> " Mixed workload " 1328300.78 >> " Random write " 790309.01 >> --- > > I'm not very familiar with iozone, but if you're only reading / > writing 100M, then probably all you're measuring is the speed of the > linux buffer cache. You should increase the amount of data to greater > than the RAM available to the system. Also, you should repeat these > runs multiple times and at a minimum take an average (and calculate > the standard deviation) of each metric to make sure you aren't getting > unusually good/bad performance. You can then compare the results using > a paired T-test to see if the difference is statistically significant. > > [snip] > >> I got this locking problem resolved after rebooting all the nodes . > > That sounds like the problem encountered in the link I sent before. > >> What I have noticed is after adding a LUN, under /dev/mpath instead of >> wwid i was seeing as: >> >> lrwxrwxrwx 1 root root 8 Aug 9 17:30 mpath13 -> ../dm-28 >> >> After reboot >> >> lrwxrwxrwx 1 root root 7 Aug 15 17:53 >> 360060e8004770d000000770d000003e9 -> ../dm-9 > > That's odd. Did you change your multipath configuration? It looks like > you've set "user_friendly_names" to "no". No. I have "yes" to user_friendly_names . I hav't change anything to multipath.conf however I can see user friendly names in multipath -ll - mpath13 (360060e8004770d000000770d000003e9) dm-9 HITACHI,OPEN-V*4 [size=2.0T][features=1 queue_if_no_path][hwhandler=0][rw] \_ round-robin 0 [prio=2][active] \_ 5:0:1:7 sdl 8:176 [active][ready] \_ 6:0:1:7 sdu 65:64 [active][ready] - Paras. > >> Thanks >> Paras. > -- > Jonathan Barber <jonathan.barber@xxxxxxxxx> > > -- > Linux-cluster mailing list > Linux-cluster@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/linux-cluster > -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
