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 >> >> >> >> > > >
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