Hi all I heard somewhere about oversubscribing issue related to ost thread, but i just wonder why i calculated followed the function that i founded in the manual ( *thread_number = RAM * CPU core / 128 MB* - do correct me if there's something wrong with it, please ) , the oversubscribing warning is still appears.
Maybe i have to choose my own value from trial and error, but is there any explanation for this situation? @Erik : could u please describe your bottleneck problem with journal device for me ? as detail as better ? On Tue, Jan 26, 2010 at 10:00 PM, Erik Froese <[email protected]> wrote: > Sorry Lex I misread your email. I saw similar messages about my journal > devices. The OST is an ext3+extra features filesystem. Each FS has an > associated journal that CAN be on a separate device. Its supposed to speed > up small file operations. Mine were oversubscribed and became a bottleneck. > > Erik > > > On Mon, Jan 25, 2010 at 11:40 AM, Lex <[email protected]> wrote: > >> Sorry Erik if i'm rising such a "bad" question, could u tell me more about >> OST journal device ? I even don't know what it is as well as haven't seen it >> before, in the lustre manual. >> >> Best regards >> >> >> On Mon, Jan 25, 2010 at 10:52 PM, Erik Froese <[email protected]>wrote: >> >>> Is each OST journals on its own physical disk? I've seen those messages >>> when there isn't enough hardware dedicated to the journal device. >>> Erik >>> >>> On Sun, Jan 24, 2010 at 11:43 PM, Aaron Knister <[email protected] >>> > wrote: >>> >>>> I don't necessarily think there's anything wrong with using drbd or >>>> running it over gigabit ethernet. If you stop all I/O to the lustre >>>> filesystem, what does an hdparm -t show on the sdc and drbd devices? Do you >>>> have any performance numbers for the drbd or underlying raid devices? >>>> >>>> On Jan 24, 2010, at 11:17 PM, Lex wrote: >>>> >>>> Thank you for your fast reply, Aaron >>>> >>>> I'm using Giga Ethernet to synchronize data between to our fail-over >>>> node. Is there something wrong ? Tell me, please >>>> >>>> On Mon, Jan 25, 2010 at 10:35 AM, Aaron Knister < >>>> [email protected]> wrote: >>>> >>>>> My best guess (and please correct me if I'm wrong) is that those >>>>> messages are because the underlying block devices are slow to respond to >>>>> i/o >>>>> requests. It looks like you're using DRBD. What's your interconnect? >>>>> >>>>> On Jan 24, 2010, at 9:42 PM, Lex wrote: >>>>> >>>>> Hi list >>>>> >>>>> I have one OSS with hadware info like this : >>>>> >>>>> CPU Intel(R) xeon E5420 2.5 Ghz >>>>> Chipset intel 5000P >>>>> 8GB RAM >>>>> >>>>> With this OSS, we using 2 RAID-5 arrays as OSTs ( each has 4 x 1.5 TB >>>>> hard drive with RAID controller adaptec 5805 ) >>>>> >>>>> I worked quite smooth before, but, about 2 weeks ago, in >>>>> /var/log/messages, i saw many warning ( i thought so) like this: >>>>> >>>>> *Jan 25 08:41:23 OST6 kernel: Lustre: >>>>> 9587:0:(filter_io_26.c:706:filter_commitrw_write()) lustre-OST0006: slow >>>>> direct_io 35s >>>>> Jan 25 08:41:34 OST6 kernel: Lustre: >>>>> 9608:0:(filter_io_26.c:706:filter_commitrw_write()) lustre-OST0006: slow >>>>> direct_io 41s >>>>> Jan 25 08:41:34 OST6 kernel: Lustre: >>>>> 9608:0:(filter_io_26.c:706:filter_commitrw_write()) Skipped 2 previous >>>>> similar messages >>>>> Jan 25 08:41:35 OST6 kernel: Lustre: >>>>> 9645:0:(filter_io_26.c:706:filter_commitrw_write()) lustre-OST0006: slow >>>>> direct_io 43s >>>>> Jan 25 08:58:10 OST6 kernel: Lustre: >>>>> 9646:0:(filter_io_26.c:706:filter_commitrw_write()) lustre-OST0006: slow >>>>> direct_io 31s >>>>> Jan 25 08:59:39 OST6 kernel: Lustre: >>>>> 9609:0:(filter_io_26.c:706:filter_commitrw_write()) lustre-OST0006: slow >>>>> direct_io 30s >>>>> Jan 25 09:01:05 OST6 kernel: Lustre: >>>>> 9587:0:(filter_io_26.c:706:filter_commitrw_write()) lustre-OST0006: slow >>>>> direct_io 33s >>>>> Jan 25 09:03:23 OST6 kernel: Lustre: >>>>> 9633:0:(filter_io_26.c:706:filter_commitrw_write()) lustre-OST0006: slow >>>>> direct_io 32s >>>>> Jan 25 09:11:25 OST6 kernel: Lustre: >>>>> 9585:0:(filter_io_26.c:706:filter_commitrw_write()) lustre-OST0006: slow >>>>> direct_io 36s* >>>>> >>>>> I googled around and found that it's because a problem with >>>>> oss_num_threads and even though brought it down to 64 ( followed by the >>>>> function i found in the 1.8 manual: thread_number = RAM * CPU core / 128 >>>>> MB, >>>>> its value is 256 ) >>>>> >>>>> *options ost oss_num_threads=64* >>>>> >>>>> It still didn't help. >>>>> >>>>> I thought it was only the harmless warning but maybe wrong, our >>>>> performance is goes down quite heavily ( it's maybe because of other >>>>> reason, >>>>> but for now, i am only doubting slow direct_io problem ) >>>>> >>>>> iostat -m 1 1 >>>>> Linux 2.6.18-92.1.17.el5_lustre.1.8.0custom (OST6) 01/25/2010 >>>>> >>>>> avg-cpu: %user %nice %system %iowait %steal %idle >>>>> 0.01 0.02 2.86 25.01 0.00 72.10 >>>>> >>>>> Device: tps MB_read/s MB_wrtn/s MB_read MB_wrtn >>>>> sda 1.30 0.01 0.00 11386 3469 >>>>> sdb 1.30 0.01 0.00 11531 3469 >>>>> sdc 131.50 *12.40* 0.26 11793218 >>>>> 249934 >>>>> sdd 178.46 *18.00* 0.26 17124065 >>>>> 250334 >>>>> md2 3.33 0.02 0.00 22915 2634 >>>>> md1 0.00 0.00 0.00 0 0 >>>>> md0 0.00 0.00 0.00 0 0 >>>>> drbd3 480.10 *12.39* 0.26 11789047 >>>>> 249639 >>>>> drbd6 565.85 *14.89* 0.26 14168452 >>>>> 249211 >>>>> >>>>> >>>>> So, could anyone please tell me whether it's warning impact our system >>>>> performance or not ? and if it does, give me solution or advice to resolve >>>>> it, please >>>>> >>>>> Best regards >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> _______________________________________________ >>>>> Lustre-discuss mailing list >>>>> [email protected] >>>>> http://lists.lustre.org/mailman/listinfo/lustre-discuss >>>>> >>>>> >>>>> >>>> >>>> >>>> _______________________________________________ >>>> Lustre-discuss mailing list >>>> [email protected] >>>> http://lists.lustre.org/mailman/listinfo/lustre-discuss >>>> >>>> >>> >> >
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