Hi! The clients are KVM VMs, there's QEMU/libvirt impact for sure. I will test with a baremetal client and see whether it performs much better. /Z On Wed, 6 Oct 2021, 01:29 Anthony D'Atri, <anthony.datri@xxxxxxxxx> wrote: > The lead PG handling ops isn’t a factor, with RBD your volumes touch > dozens / hundreds of PGs. But QD=1 and small block sizes are going to > limit your throughput. > > What are your clients? Are they bare metal? Are they VMs? If they’re > VMs, do you have QEMU/libvirt throttling in play? I see that a lot. > > > On Oct 5, 2021, at 2:06 PM, Zakhar Kirpichenko <zakhar@xxxxxxxxx> wrote: > > > > I'm not sure, fio might be showing some bogus values in the summary, I'll > > check the readings again tomorrow. > > > > Another thing I noticed is that writes seem bandwidth-limited and don't > > scale well with block size and/or number of threads. I.e. one clients > > writes at about the same speed regardless of the benchmark settings. A > > person on reddit, where I asked this question as well, suggested that in > a > > replicated pool writes and reads are handled by the primary PG, which > would > > explain this write bandwidth limit. > > > > /Z > > > > On Tue, 5 Oct 2021, 22:31 Christian Wuerdig, < > christian.wuerdig@xxxxxxxxx> > > wrote: > > > >> Maybe some info is missing but 7k write IOPs at 4k block size seem > fairly > >> decent (as you also state) - the bandwidth automatically follows from > that > >> so not sure what you're expecting? > >> I am a bit puzzled though - by my math 7k IOPS at 4k should only be > >> 27MiB/sec - not sure how the 120MiB/sec was achieved > >> The read benchmark seems in line with 13k IOPS at 4k making around > >> 52MiB/sec bandwidth which again is expected. > >> > >> > >> On Wed, 6 Oct 2021 at 04:08, Zakhar Kirpichenko <zakhar@xxxxxxxxx> > wrote: > >> > >>> Hi, > >>> > >>> I built a CEPH 16.2.x cluster with relatively fast and modern hardware, > >>> and > >>> its performance is kind of disappointing. I would very much appreciate > an > >>> advice and/or pointers :-) > >>> > >>> The hardware is 3 x Supermicro SSG-6029P nodes, each equipped with: > >>> > >>> 2 x Intel(R) Xeon(R) Gold 5220R CPUs > >>> 384 GB RAM > >>> 2 x boot drives > >>> 2 x 1.6 TB Micron 7300 MTFDHBE1T6TDG drives (DB/WAL) > >>> 2 x 6.4 TB Micron 7300 MTFDHBE6T4TDG drives (storage tier) > >>> 9 x Toshiba MG06SCA10TE 9TB HDDs, write cache off (storage tier) > >>> 2 x Intel XL710 NICs connected to a pair of 40/100GE switches > >>> > >>> All 3 nodes are running Ubuntu 20.04 LTS with the latest 5.4 kernel, > >>> apparmor is disabled, energy-saving features are disabled. The network > >>> between the CEPH nodes is 40G, CEPH access network is 40G, the average > >>> latencies are < 0.15 ms. I've personally tested the network for > >>> throughput, > >>> latency and loss, and can tell that it's operating as expected and > doesn't > >>> exhibit any issues at idle or under load. > >>> > >>> The CEPH cluster is set up with 2 storage classes, NVME and HDD, with 2 > >>> smaller NVME drives in each node used as DB/WAL and each HDD allocated > . > >>> ceph osd tree output: > >>> > >>> ID CLASS WEIGHT TYPE NAME STATUS REWEIGHT > PRI-AFF > >>> -1 288.37488 root default > >>> -13 288.37488 datacenter ste > >>> -14 288.37488 rack rack01 > >>> -7 96.12495 host ceph01 > >>> 0 hdd 9.38680 osd.0 up 1.00000 > 1.00000 > >>> 1 hdd 9.38680 osd.1 up 1.00000 > 1.00000 > >>> 2 hdd 9.38680 osd.2 up 1.00000 > 1.00000 > >>> 3 hdd 9.38680 osd.3 up 1.00000 > 1.00000 > >>> 4 hdd 9.38680 osd.4 up 1.00000 > 1.00000 > >>> 5 hdd 9.38680 osd.5 up 1.00000 > 1.00000 > >>> 6 hdd 9.38680 osd.6 up 1.00000 > 1.00000 > >>> 7 hdd 9.38680 osd.7 up 1.00000 > 1.00000 > >>> 8 hdd 9.38680 osd.8 up 1.00000 > 1.00000 > >>> 9 nvme 5.82190 osd.9 up 1.00000 > 1.00000 > >>> 10 nvme 5.82190 osd.10 up 1.00000 > 1.00000 > >>> -10 96.12495 host ceph02 > >>> 11 hdd 9.38680 osd.11 up 1.00000 > 1.00000 > >>> 12 hdd 9.38680 osd.12 up 1.00000 > 1.00000 > >>> 13 hdd 9.38680 osd.13 up 1.00000 > 1.00000 > >>> 14 hdd 9.38680 osd.14 up 1.00000 > 1.00000 > >>> 15 hdd 9.38680 osd.15 up 1.00000 > 1.00000 > >>> 16 hdd 9.38680 osd.16 up 1.00000 > 1.00000 > >>> 17 hdd 9.38680 osd.17 up 1.00000 > 1.00000 > >>> 18 hdd 9.38680 osd.18 up 1.00000 > 1.00000 > >>> 19 hdd 9.38680 osd.19 up 1.00000 > 1.00000 > >>> 20 nvme 5.82190 osd.20 up 1.00000 > 1.00000 > >>> 21 nvme 5.82190 osd.21 up 1.00000 > 1.00000 > >>> -3 96.12495 host ceph03 > >>> 22 hdd 9.38680 osd.22 up 1.00000 > 1.00000 > >>> 23 hdd 9.38680 osd.23 up 1.00000 > 1.00000 > >>> 24 hdd 9.38680 osd.24 up 1.00000 > 1.00000 > >>> 25 hdd 9.38680 osd.25 up 1.00000 > 1.00000 > >>> 26 hdd 9.38680 osd.26 up 1.00000 > 1.00000 > >>> 27 hdd 9.38680 osd.27 up 1.00000 > 1.00000 > >>> 28 hdd 9.38680 osd.28 up 1.00000 > 1.00000 > >>> 29 hdd 9.38680 osd.29 up 1.00000 > 1.00000 > >>> 30 hdd 9.38680 osd.30 up 1.00000 > 1.00000 > >>> 31 nvme 5.82190 osd.31 up 1.00000 > 1.00000 > >>> 32 nvme 5.82190 osd.32 up 1.00000 > 1.00000 > >>> > >>> ceph df: > >>> > >>> --- RAW STORAGE --- > >>> CLASS SIZE AVAIL USED RAW USED %RAW USED > >>> hdd 253 TiB 241 TiB 13 TiB 13 TiB 5.00 > >>> nvme 35 TiB 35 TiB 82 GiB 82 GiB 0.23 > >>> TOTAL 288 TiB 276 TiB 13 TiB 13 TiB 4.42 > >>> > >>> --- POOLS --- > >>> POOL ID PGS STORED OBJECTS USED %USED MAX > >>> AVAIL > >>> images 12 256 24 GiB 3.15k 73 GiB 0.03 76 > >>> TiB > >>> volumes 13 256 839 GiB 232.16k 2.5 TiB 1.07 76 > >>> TiB > >>> backups 14 256 31 GiB 8.56k 94 GiB 0.04 76 > >>> TiB > >>> vms 15 256 752 GiB 198.80k 2.2 TiB 0.96 76 > >>> TiB > >>> device_health_metrics 16 32 35 MiB 39 106 MiB 0 76 > >>> TiB > >>> volumes-nvme 17 256 28 GiB 7.21k 81 GiB 0.24 11 > >>> TiB > >>> ec-volumes-meta 18 256 27 KiB 4 92 KiB 0 76 > >>> TiB > >>> ec-volumes-data 19 256 8 KiB 1 12 KiB 0 152 > >>> TiB > >>> > >>> Please disregard the ec-pools, as they're not currently in use. All > other > >>> pools are configured with min_size=2, size=3. All pools are bound to > HDD > >>> storage except for 'volumes-nvme', which is bound to NVME. The number > of > >>> PGs was increased recently, as with autoscaler I was getting a very > uneven > >>> PG distribution on devices and we're expecting to add 3 more nodes of > >>> exactly the same configuration in the coming weeks. I have to emphasize > >>> that I tested different PG numbers and they didn't have a noticeable > >>> impact > >>> on the cluster performance. > >>> > >>> The main issue is that this beautiful cluster isn't very fast. When I > test > >>> against the 'volumes' pool, residing on HDD storage class (HDDs with > >>> DB/WAL > >>> on NVME), I get unexpectedly low throughput numbers: > >>> > >>>> rados -p volumes bench 30 write --no-cleanup > >>> ... > >>> Total time run: 30.3078 > >>> Total writes made: 3731 > >>> Write size: 4194304 > >>> Object size: 4194304 > >>> Bandwidth (MB/sec): 492.415 > >>> Stddev Bandwidth: 161.777 > >>> Max bandwidth (MB/sec): 820 > >>> Min bandwidth (MB/sec): 204 > >>> Average IOPS: 123 > >>> Stddev IOPS: 40.4442 > >>> Max IOPS: 205 > >>> Min IOPS: 51 > >>> Average Latency(s): 0.129115 > >>> Stddev Latency(s): 0.143881 > >>> Max latency(s): 1.35669 > >>> Min latency(s): 0.0228179 > >>> > >>>> rados -p volumes bench 30 seq --no-cleanup > >>> ... > >>> Total time run: 14.7272 > >>> Total reads made: 3731 > >>> Read size: 4194304 > >>> Object size: 4194304 > >>> Bandwidth (MB/sec): 1013.36 > >>> Average IOPS: 253 > >>> Stddev IOPS: 63.8709 > >>> Max IOPS: 323 > >>> Min IOPS: 91 > >>> Average Latency(s): 0.0625202 > >>> Max latency(s): 0.551629 > >>> Min latency(s): 0.010683 > >>> > >>> On average, I get around 550 MB/s writes and 800 MB/s reads with 16 > >>> threads > >>> and 4MB blocks. The numbers don't look fantastic for this hardware, I > can > >>> actually push over 8 GB/s of throughput with fio, 16 threads and 4MB > >>> blocks > >>> from an RBD client (KVM Linux VM) connected over a low-latency 40G > >>> network, > >>> probably hitting some OSD caches there: > >>> > >>> READ: bw=8525MiB/s (8939MB/s), 58.8MiB/s-1009MiB/s > (61.7MB/s-1058MB/s), > >>> io=501GiB (538GB), run=60001-60153msec > >>> Disk stats (read/write): > >>> vdc: ios=48163/0, merge=6027/0, ticks=1400509/0, in_queue=1305092, > >>> util=99.48% > >>> > >>> The issue manifests when the same client does something closer to > >>> real-life > >>> usage, like a single-thread write or read with 4KB blocks, as if using > for > >>> example ext4 file system: > >>> > >>>> fio --name=ttt --ioengine=posixaio --rw=write --bs=4k --numjobs=1 > >>> --size=4g --iodepth=1 --runtime=60 --time_based --end_fsync=1 > >>> ... > >>> Run status group 0 (all jobs): > >>> WRITE: bw=120MiB/s (126MB/s), 120MiB/s-120MiB/s (126MB/s-126MB/s), > >>> io=7694MiB (8067MB), run=64079-64079msec > >>> Disk stats (read/write): > >>> vdc: ios=0/6985, merge=0/406, ticks=0/3062535, in_queue=3048216, > >>> util=77.31% > >>> > >>>> fio --name=ttt --ioengine=posixaio --rw=read --bs=4k --numjobs=1 > >>> --size=4g --iodepth=1 --runtime=60 --time_based --end_fsync=1 > >>> ... > >>> Run status group 0 (all jobs): > >>> READ: bw=54.0MiB/s (56.7MB/s), 54.0MiB/s-54.0MiB/s > (56.7MB/s-56.7MB/s), > >>> io=3242MiB (3399MB), run=60001-60001msec > >>> Disk stats (read/write): > >>> vdc: ios=12952/3, merge=0/1, ticks=81706/1, in_queue=56336, > util=99.13% > >>> > >>> And this is a total disaster: the IOPS look decent, but the bandwidth > is > >>> unexpectedly very very low. I just don't understand why a single RBD > >>> client > >>> writes at 120 MB/s (sometimes slower), and 50 MB/s reads look like a > bad > >>> joke ¯\_(ツ)_/¯ > >>> > >>> When I run these benchmarks, nothing seems to be overloaded, things > like > >>> CPU and network are barely utilized, OSD latencies don't show anything > >>> unusual. Thus I am puzzled with these results, as in my opinion SAS > HDDs > >>> with DB/WAL on NVME drives should produce better I/O bandwidth, both > for > >>> writes and reads. I mean, I can easily get much better performance > from a > >>> single HDD shared over network via NFS or iSCSI. > >>> > >>> I am open to suggestions and would very much appreciate comments > and/or an > >>> advice on how to improve the cluster performance. > >>> > >>> Best regards, > >>> Zakhar > >>> _______________________________________________ > >>> ceph-users mailing list -- ceph-users@xxxxxxx > >>> To unsubscribe send an email to ceph-users-leave@xxxxxxx > >>> > >> > > _______________________________________________ > > ceph-users mailing list -- ceph-users@xxxxxxx > > To unsubscribe send an email to ceph-users-leave@xxxxxxx > > _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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