36 OSDs Each of 4 storage servers has 9 1TB SSD drives, each drive as 1 osd (no RAID) == 36 OSDs 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
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-tes >> t-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 >>> >>> >>> >>> >> >> >> > > >
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