Have you ruled out the disk controller and backplane in the server running slower?
On Thu, Oct 19, 2017 at 4:42 PM Russell Glaue <rgl...@cait.org> wrote: > I ran the test on the Ceph pool, and ran atop on all 4 storage servers, as > suggested. > > Out of the 4 servers: > 3 of them performed with 17% to 30% disk %busy, and 11% CPU wait. > Momentarily spiking up to 50% on one server, and 80% on another > The 2nd newest server was almost averaging 90% disk %busy and 150% CPU > wait. And more than momentarily spiking to 101% disk busy and 250% CPU wait. > For this 2nd newest server, this was the statistics for about 8 of 9 > disks, with the 9th disk not far behind the others. > > I cannot believe all 9 disks are bad > They are the same disks as the newest 1st server, Crucial_CT960M500SSD1, > and same exact server hardware too. > They were purchased at the same time in the same purchase order and > arrived at the same time. > So I cannot believe I just happened to put 9 bad disks in one server, and > 9 good ones in the other. > > I know I have Ceph configured exactly the same on all servers > And I am sure I have the hardware settings configured exactly the same on > the 1st and 2nd servers. > So if I were someone else, I would say it maybe is bad hardware on the 2nd > server. > But the 2nd server is running very well without any hint of a problem. > > Any other ideas or suggestions? > > -RG > > > On Wed, Oct 18, 2017 at 3:40 PM, Maged Mokhtar <mmokh...@petasan.org> > wrote: > >> just run the same 32 threaded rados test as you did before and this time >> run atop while the test is running looking for %busy of cpu/disks. It >> should give an idea if there is a bottleneck in them. >> >> On 2017-10-18 21:35, Russell Glaue wrote: >> >> I cannot run the write test reviewed at >> the ceph-how-to-test-if-your-ssd-is-suitable-as-a-journal-device blog. The >> tests write directly to the raw disk device. >> Reading an infile (created with urandom) on one SSD, writing the outfile >> to another osd, yields about 17MB/s. >> But Isn't this write speed limited by the speed in which in the dd infile >> can be read? >> And I assume the best test should be run with no other load. >> >> How does one run the rados bench "as stress"? >> >> -RG >> >> >> On Wed, Oct 18, 2017 at 1:33 PM, Maged Mokhtar <mmokh...@petasan.org> >> wrote: >> >>> measuring resource load as outlined earlier will show if the drives are >>> performing well or not. Also how many osds do you have ? >>> >>> On 2017-10-18 19:26, Russell Glaue wrote: >>> >>> The SSD drives are Crucial M500 >>> A Ceph user did some benchmarks and found it had good performance >>> >>> https://forum.proxmox.com/threads/ceph-bad-performance-in-qemu-guests.21551/ >>> >>> However, a user comment from 3 years ago on the blog post you linked to >>> says to avoid the Crucial M500 >>> >>> Yet, this performance posting tells that the Crucial M500 is good. >>> https://inside.servers.com/ssd-performance-2017-c4307a92dea >>> >>> On Wed, Oct 18, 2017 at 11:53 AM, Maged Mokhtar <mmokh...@petasan.org> >>> wrote: >>> >>>> Check out the following link: some SSDs perform bad in Ceph due to sync >>>> writes to journal >>>> >>>> >>>> https://www.sebastien-han.fr/blog/2014/10/10/ceph-how-to-test-if-your-ssd-is-suitable-as-a-journal-device/ >>>> >>>> Anther thing that can help is to re-run the rados 32 threads as stress >>>> and view resource usage using atop (or collectl/sar) to check for %busy cpu >>>> and %busy disks to give you an idea of what is holding down your >>>> cluster..for example: if cpu/disk % are all low then check your >>>> network/switches. If disk %busy is high (90%) for all disks then your >>>> disks are the bottleneck: which either means you have SSDs that are not >>>> suitable for Ceph or you have too few disks (which i doubt is the case). If >>>> only 1 disk %busy is high, there may be something wrong with this disk >>>> should be removed. >>>> >>>> Maged >>>> >>>> On 2017-10-18 18:13, Russell Glaue wrote: >>>> >>>> In my previous post, in one of my points I was wondering if the request >>>> size would increase if I enabled jumbo packets. currently it is disabled. >>>> >>>> @jdillama: The qemu settings for both these two guest machines, with >>>> RAID/LVM and Ceph/rbd images, are the same. I am not thinking that changing >>>> the qemu settings of "min_io_size=<limited to 16bits>,opt_io_size=<RBD >>>> image object size>" will directly address the issue. >>>> >>>> @mmokhtar: Ok. So you suggest the request size is the result of the >>>> problem and not the cause of the problem. meaning I should go after a >>>> different issue. >>>> >>>> I have been trying to get write speeds up to what people on this mail >>>> list are discussing. >>>> It seems that for our configuration, as it matches others, we should be >>>> getting about 70MB/s write speed. >>>> But we are not getting that. >>>> Single writes to disk are lucky to get 5MB/s to 6MB/s, but are >>>> typically 1MB/s to 2MB/s. >>>> Monitoring the entire Ceph cluster (using http://cephdash.crapworks.de/), >>>> I have seen very rare momentary spikes up to 30MB/s. >>>> >>>> My storage network is connected via a 10Gb switch >>>> I have 4 storage servers with a LSI Logic MegaRAID SAS 2208 controller >>>> Each storage server has 9 1TB SSD drives, each drive as 1 osd (no RAID) >>>> Each drive is one LVM group, with two volumes - one volume for the osd, >>>> one volume for the journal >>>> Each osd is formatted with xfs >>>> The crush map is simple: default->rack->[host[1..4]->osd] with an >>>> evenly distributed weight >>>> The redundancy is triple replication >>>> >>>> While I have read comments that having the osd and journal on the same >>>> disk decreases write speed, I have also read that once past 8 OSDs per node >>>> this is the recommended configuration, however this is also the reason why >>>> SSD drives are used exclusively for OSDs in the storage nodes. >>>> None-the-less, I was still expecting write speeds to be above 30MB/s, >>>> not below 6MB/s. >>>> Even at 12x slower than the RAID, using my previously posted iostat >>>> data set, I should be seeing write speeds that average 10MB/s, not 2MB/s. >>>> >>>> In regards to the rados benchmark tests you asked me to run, here is >>>> the output: >>>> >>>> [centos7]# rados bench -p scbench -b 4096 30 write -t 1 >>>> Maintaining 1 concurrent writes of 4096 bytes to objects of size 4096 >>>> for up to 30 seconds or 0 objects >>>> Object prefix: benchmark_data_hamms.sys.cu.cait.org_85049 >>>> sec Cur ops started finished avg MB/s cur MB/s last lat(s) avg >>>> lat(s) >>>> 0 0 0 0 0 0 - >>>> 0 >>>> 1 1 201 200 0.78356 0.78125 0.00522307 >>>> 0.00496574 >>>> 2 1 469 468 0.915303 1.04688 0.00437497 >>>> 0.00426141 >>>> 3 1 741 740 0.964371 1.0625 0.00512853 >>>> 0.0040434 >>>> 4 1 888 887 0.866739 0.574219 0.00307699 >>>> 0.00450177 >>>> 5 1 1147 1146 0.895725 1.01172 0.00376454 >>>> 0.0043559 >>>> 6 1 1325 1324 0.862293 0.695312 0.00459443 >>>> 0.004525 >>>> 7 1 1494 1493 0.83339 0.660156 0.00461002 >>>> 0.00458452 >>>> 8 1 1736 1735 0.847369 0.945312 0.00253971 >>>> 0.00460458 >>>> 9 1 1998 1997 0.866922 1.02344 0.00236573 >>>> 0.00450172 >>>> 10 1 2260 2259 0.882563 1.02344 0.00262179 >>>> 0.00442152 >>>> 11 1 2526 2525 0.896775 1.03906 0.00336914 >>>> 0.00435092 >>>> 12 1 2760 2759 0.898203 0.914062 0.00351827 >>>> 0.00434491 >>>> 13 1 3016 3015 0.906025 1 0.00335703 >>>> 0.00430691 >>>> 14 1 3257 3256 0.908545 0.941406 0.00332344 >>>> 0.00429495 >>>> 15 1 3490 3489 0.908644 0.910156 0.00318815 >>>> 0.00426387 >>>> 16 1 3728 3727 0.909952 0.929688 0.0032881 >>>> 0.00428895 >>>> 17 1 3986 3985 0.915703 1.00781 0.00274809 >>>> 0.0042614 >>>> 18 1 4250 4249 0.922116 1.03125 0.00287411 >>>> 0.00423214 >>>> 19 1 4505 4504 0.926003 0.996094 0.00375435 >>>> 0.00421442 >>>> 2017-10-18 10:56:31.267173 min lat: 0.00181259 max lat: 0.270553 avg >>>> lat: 0.00420118 >>>> sec Cur ops started finished avg MB/s cur MB/s last lat(s) avg >>>> lat(s) >>>> 20 1 4757 4756 0.928915 0.984375 0.00463972 >>>> 0.00420118 >>>> 21 1 5009 5008 0.93155 0.984375 0.00360065 >>>> 0.00418937 >>>> 22 1 5235 5234 0.929329 0.882812 0.00626214 >>>> 0.004199 >>>> 23 1 5500 5499 0.933925 1.03516 0.00466584 >>>> 0.00417836 >>>> 24 1 5708 5707 0.928861 0.8125 0.00285727 >>>> 0.00420146 >>>> 25 0 5964 5964 0.931858 1.00391 0.00417383 >>>> 0.0041881 >>>> 26 1 6216 6215 0.933722 0.980469 0.0041009 >>>> 0.00417915 >>>> 27 1 6481 6480 0.937474 1.03516 0.00307484 >>>> 0.00416118 >>>> 28 1 6745 6744 0.940819 1.03125 0.00266329 >>>> 0.00414777 >>>> 29 1 7003 7002 0.943124 1.00781 0.00305905 >>>> 0.00413758 >>>> 30 1 7271 7270 0.946578 1.04688 0.00391017 >>>> 0.00412238 >>>> Total time run: 30.006060 >>>> Total writes made: 7272 >>>> Write size: 4096 >>>> Object size: 4096 >>>> Bandwidth (MB/sec): 0.946684 >>>> Stddev Bandwidth: 0.123762 >>>> Max bandwidth (MB/sec): 1.0625 >>>> Min bandwidth (MB/sec): 0.574219 >>>> Average IOPS: 242 >>>> Stddev IOPS: 31 >>>> Max IOPS: 272 >>>> Min IOPS: 147 >>>> Average Latency(s): 0.00412247 >>>> Stddev Latency(s): 0.00648437 >>>> Max latency(s): 0.270553 >>>> Min latency(s): 0.00175318 >>>> Cleaning up (deleting benchmark objects) >>>> Clean up completed and total clean up time :29.069423 >>>> >>>> [centos7]# rados bench -p scbench -b 4096 30 write -t 32 >>>> Maintaining 32 concurrent writes of 4096 bytes to objects of size 4096 >>>> for up to 30 seconds or 0 objects >>>> Object prefix: benchmark_data_hamms.sys.cu.cait.org_86076 >>>> sec Cur ops started finished avg MB/s cur MB/s last lat(s) avg >>>> lat(s) >>>> 0 0 0 0 0 0 - >>>> 0 >>>> 1 32 3013 2981 11.6438 11.6445 0.00247906 >>>> 0.00572026 >>>> 2 32 5349 5317 10.3834 9.125 0.00246662 >>>> 0.00932016 >>>> 3 32 5707 5675 7.3883 1.39844 0.00389774 >>>> 0.0156726 >>>> 4 32 5895 5863 5.72481 0.734375 1.13137 >>>> 0.0167946 >>>> 5 32 6869 6837 5.34068 3.80469 0.0027652 >>>> 0.0226577 >>>> 6 32 8901 8869 5.77306 7.9375 0.0053211 >>>> 0.0216259 >>>> 7 32 10800 10768 6.00785 7.41797 0.00358187 >>>> 0.0207418 >>>> 8 32 11825 11793 5.75728 4.00391 0.00217575 >>>> 0.0215494 >>>> 9 32 12941 12909 5.6019 4.35938 0.00278512 >>>> 0.0220567 >>>> 10 32 13317 13285 5.18849 1.46875 0.0034973 >>>> 0.0240665 >>>> 11 32 16189 16157 5.73653 11.2188 0.00255841 >>>> 0.0212708 >>>> 12 32 16749 16717 5.44077 2.1875 0.00330334 >>>> 0.0215915 >>>> 13 32 16756 16724 5.02436 0.0273438 0.00338994 >>>> 0.021849 >>>> 14 32 17908 17876 4.98686 4.5 0.00402598 >>>> 0.0244568 >>>> 15 32 17936 17904 4.66171 0.109375 0.00375799 >>>> 0.0245545 >>>> 16 32 18279 18247 4.45409 1.33984 0.00483873 >>>> 0.0267929 >>>> 17 32 18372 18340 4.21346 0.363281 0.00505187 >>>> 0.0275887 >>>> 18 32 19403 19371 4.20309 4.02734 0.00545154 >>>> 0.029348 >>>> 19 31 19845 19814 4.07295 1.73047 0.00254726 >>>> 0.0306775 >>>> 2017-10-18 10:57:58.160536 min lat: 0.0015005 max lat: 2.27707 avg lat: >>>> 0.0307559 >>>> sec Cur ops started finished avg MB/s cur MB/s last lat(s) avg >>>> lat(s) >>>> 20 31 20401 20370 3.97788 2.17188 0.00307238 >>>> 0.0307559 >>>> 21 32 21338 21306 3.96254 3.65625 0.00464563 >>>> 0.0312288 >>>> 22 32 23057 23025 4.0876 6.71484 0.00296295 >>>> 0.0299267 >>>> 23 32 23057 23025 3.90988 0 - >>>> 0.0299267 >>>> 24 32 23803 23771 3.86837 1.45703 0.00301471 >>>> 0.0312804 >>>> 25 32 24112 24080 3.76191 1.20703 0.00191063 >>>> 0.0331462 >>>> 26 31 25303 25272 3.79629 4.65625 0.00794399 >>>> 0.0329129 >>>> 27 32 28803 28771 4.16183 13.668 0.0109817 >>>> 0.0297469 >>>> 28 32 29592 29560 4.12325 3.08203 0.00188185 >>>> 0.0301911 >>>> 29 32 30595 30563 4.11616 3.91797 0.00379099 >>>> 0.0296794 >>>> 30 32 31031 30999 4.03572 1.70312 0.00283347 >>>> 0.0302411 >>>> Total time run: 30.822350 >>>> Total writes made: 31032 >>>> Write size: 4096 >>>> Object size: 4096 >>>> Bandwidth (MB/sec): 3.93282 >>>> Stddev Bandwidth: 3.66265 >>>> Max bandwidth (MB/sec): 13.668 >>>> Min bandwidth (MB/sec): 0 >>>> Average IOPS: 1006 >>>> Stddev IOPS: 937 >>>> Max IOPS: 3499 >>>> Min IOPS: 0 >>>> Average Latency(s): 0.0317779 >>>> Stddev Latency(s): 0.164076 >>>> Max latency(s): 2.27707 >>>> Min latency(s): 0.0013848 >>>> Cleaning up (deleting benchmark objects) >>>> Clean up completed and total clean up time :20.166559 >>>> >>>> >>>> >>>> >>>> On Wed, Oct 18, 2017 at 8:51 AM, Maged Mokhtar <mmokh...@petasan.org> >>>> wrote: >>>> >>>>> First a general comment: local RAID will be faster than Ceph for a >>>>> single threaded (queue depth=1) io operation test. A single thread Ceph >>>>> client will see at best same disk speed for reads and for writes 4-6 times >>>>> slower than single disk. Not to mention the latency of local disks will >>>>> much better. Where Ceph shines is when you have many concurrent ios, it >>>>> scales whereas RAID will decrease speed per client as you add more. >>>>> >>>>> Having said that, i would recommend running rados/rbd bench-write and >>>>> measure 4k iops at 1 and 32 threads to get a better idea of how your >>>>> cluster performs: >>>>> >>>>> ceph osd pool create testpool 256 256 >>>>> rados bench -p testpool -b 4096 30 write -t 1 >>>>> rados bench -p testpool -b 4096 30 write -t 32 >>>>> ceph osd pool delete testpool testpool --yes-i-really-really-mean-it >>>>> >>>>> rbd bench-write test-image --io-threads=1 --io-size 4096 --io-pattern >>>>> rand --rbd_cache=false >>>>> rbd bench-write test-image --io-threads=32 --io-size 4096 --io-pattern >>>>> rand --rbd_cache=false >>>>> >>>>> I think the request size difference you see is due to the io scheduler >>>>> in the case of local disks having more ios to re-group so has a better >>>>> chance in generating larger requests. Depending on your kernel, the io >>>>> scheduler may be different for rbd (blq-mq) vs sdx (cfq) but again i would >>>>> think the request size is a result not a cause. >>>>> >>>>> Maged >>>>> >>>>> On 2017-10-17 23:12, Russell Glaue wrote: >>>>> >>>>> I am running ceph jewel on 5 nodes with SSD OSDs. >>>>> I have an LVM image on a local RAID of spinning disks. >>>>> I have an RBD image on in a pool of SSD disks. >>>>> Both disks are used to run an almost identical CentOS 7 system. >>>>> Both systems were installed with the same kickstart, though the disk >>>>> partitioning is different. >>>>> >>>>> I want to make writes on the the ceph image faster. For example, lots >>>>> of writes to MySQL (via MySQL replication) on a ceph SSD image are about >>>>> 10x slower than on a spindle RAID disk image. The MySQL server on ceph rbd >>>>> image has a hard time keeping up in replication. >>>>> >>>>> So I wanted to test writes on these two systems >>>>> I have a 10GB compressed (gzip) file on both servers. >>>>> I simply gunzip the file on both systems, while running iostat. >>>>> >>>>> The primary difference I see in the results is the average size of the >>>>> request to the disk. >>>>> CentOS7-lvm-raid-sata writes a lot faster to disk, and the size of the >>>>> request is about 40x, but the number of writes per second is about the >>>>> same >>>>> This makes me want to conclude that the smaller size of the request >>>>> for CentOS7-ceph-rbd-ssd system is the cause of it being slow. >>>>> >>>>> >>>>> How can I make the size of the request larger for ceph rbd images, so >>>>> I can increase the write throughput? >>>>> Would this be related to having jumbo packets enabled in my ceph >>>>> storage network? >>>>> >>>>> >>>>> Here is a sample of the results: >>>>> >>>>> [CentOS7-lvm-raid-sata] >>>>> $ gunzip large10gFile.gz & >>>>> $ iostat -x vg_root-lv_var -d 5 -m -N >>>>> Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s >>>>> avgrq-sz avgqu-sz await r_await w_await svctm %util >>>>> ... >>>>> vg_root-lv_var 0.00 0.00 30.60 452.20 13.60 222.15 >>>>> 1000.04 8.69 14.05 0.99 14.93 2.07 100.04 >>>>> vg_root-lv_var 0.00 0.00 88.20 182.00 39.20 89.43 >>>>> 974.95 4.65 9.82 0.99 14.10 3.70 100.00 >>>>> vg_root-lv_var 0.00 0.00 75.45 278.24 33.53 136.70 >>>>> 985.73 4.36 33.26 1.34 41.91 0.59 20.84 >>>>> vg_root-lv_var 0.00 0.00 111.60 181.80 49.60 89.34 >>>>> 969.84 2.60 8.87 0.81 13.81 0.13 3.90 >>>>> vg_root-lv_var 0.00 0.00 68.40 109.60 30.40 53.63 >>>>> 966.87 1.51 8.46 0.84 13.22 0.80 14.16 >>>>> ... >>>>> >>>>> [CentOS7-ceph-rbd-ssd] >>>>> $ gunzip large10gFile.gz & >>>>> $ iostat -x vg_root-lv_data -d 5 -m -N >>>>> Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s >>>>> avgrq-sz avgqu-sz await r_await w_await svctm %util >>>>> ... >>>>> vg_root-lv_data 0.00 0.00 46.40 167.80 0.88 1.46 >>>>> 22.36 1.23 5.66 2.47 6.54 4.52 96.82 >>>>> vg_root-lv_data 0.00 0.00 16.60 55.20 0.36 0.14 >>>>> 14.44 0.99 13.91 9.12 15.36 13.71 98.46 >>>>> vg_root-lv_data 0.00 0.00 69.00 173.80 1.34 1.32 >>>>> 22.48 1.25 5.19 3.77 5.75 3.94 95.68 >>>>> vg_root-lv_data 0.00 0.00 74.40 293.40 1.37 1.47 >>>>> 15.83 1.22 3.31 2.06 3.63 2.54 93.26 >>>>> vg_root-lv_data 0.00 0.00 90.80 359.00 1.96 3.41 >>>>> 24.45 1.63 3.63 1.94 4.05 2.10 94.38 >>>>> ... >>>>> >>>>> [iostat key] >>>>> w/s == The number (after merges) of write requests completed per >>>>> second for the device. >>>>> wMB/s == The number of sectors (kilobytes, megabytes) written to the >>>>> device per second. >>>>> avgrq-sz == The average size (in kilobytes) of the requests that were >>>>> issued to the device. >>>>> avgqu-sz == The average queue length of the requests that were issued >>>>> to the device. >>>>> >>>>> >>>>> _______________________________________________ >>>>> ceph-users mailing list >>>>> ceph-users@lists.ceph.com >>>>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >>>>> >>>>> >>>>> >>>>> >>>> >>>> >>>> >>> >>> >>> >> >> >> > > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >
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