As optimisation, try to set ioscheduler to noop, and also enable rbd_cache=true. (It's really helping for for sequential writes) but your results seem quite low, 926kb/s with 4k, it's only 200io/s. check if you don't have any big network latencies, or mtu fragementation problem. Maybe also try to bench with fio, with more parallel jobs. ----- Mail original ----- De: "mad Engineer" <themadengin33r@xxxxxxxxx> À: "Philippe Schwarz" <phil@xxxxxxxxxxxxxx> Cc: "ceph-users" <ceph-users@xxxxxxxxxxxxxx> Envoyé: Samedi 28 Février 2015 13:06:59 Objet: Re: Extreme slowness in SSD cluster with 3 nodes and 9 OSD with 3.16-3 kernel Thanks for the reply Philippe,we were using these disks in our NAS,now it looks like i am in big trouble :-( On Sat, Feb 28, 2015 at 5:02 PM, Philippe Schwarz <phil@xxxxxxxxxxxxxx> wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Le 28/02/2015 12:19, mad Engineer a écrit : >> Hello All, >> >> I am trying ceph-firefly 0.80.8 >> (69eaad7f8308f21573c604f121956e64679a52a7) with 9 OSD ,all Samsung >> SSD 850 EVO on 3 servers with 24 G RAM,16 cores @2.27 Ghz Ubuntu >> 14.04 LTS with 3.16-3 kernel.All are connected to 10G ports with >> maximum MTU.There are no extra disks for journaling and also there >> are no separate network for replication and data transfer.All 3 >> nodes are also hosting monitoring process.Operating system runs on >> SATA disk. >> >> When doing a sequential benchmark using "dd" on RBD, mounted on >> client as ext4 its taking 110s to write 100Mb data at an average >> speed of 926Kbps. >> >> time dd if=/dev/zero of=hello bs=4k count=25000 oflag=direct >> 25000+0 records in 25000+0 records out 102400000 bytes (102 MB) >> copied, 110.582 s, 926 kB/s >> >> real 1m50.585s user 0m0.106s sys 0m2.233s >> >> While doing this directly on ssd mount point shows: >> >> time dd if=/dev/zero of=hello bs=4k count=25000 oflag=direct >> 25000+0 records in 25000+0 records out 102400000 bytes (102 MB) >> copied, 1.38567 s, 73.9 MB/s >> >> OSDs are in XFS with these extra arguments : >> >> rw,noatime,inode64,logbsize=256k,delaylog,allocsize=4M >> >> ceph.conf >> >> [global] fsid = 7d889081-7826-439c-9fe5-d4e57480d9be >> mon_initial_members = ceph1, ceph2, ceph3 mon_host = >> 10.99.10.118,10.99.10.119,10.99.10.120 auth_cluster_required = >> cephx auth_service_required = cephx auth_client_required = cephx >> filestore_xattr_use_omap = true osd_pool_default_size = 2 >> osd_pool_default_min_size = 2 osd_pool_default_pg_num = 450 >> osd_pool_default_pgp_num = 450 max_open_files = 131072 >> >> [osd] osd_mkfs_type = xfs osd_op_threads = 8 osd_disk_threads = 4 >> osd_mount_options_xfs = >> "rw,noatime,inode64,logbsize=256k,delaylog,allocsize=4M" >> >> >> on our traditional storage with Full SAS disk, same "dd" completes >> in 16s with an average write speed of 6Mbps. >> >> Rados bench: >> >> rados bench -p rbd 10 write Maintaining 16 concurrent writes of >> 4194304 bytes for up to 10 seconds or 0 objects Object prefix: >> benchmark_data_ceph1_2977 sec Cur ops started finished avg MB/s >> cur MB/s last lat avg lat 0 0 0 0 >> 0 0 - 0 1 16 94 78 >> 311.821 312 0.041228 0.140132 2 16 192 176 >> 351.866 392 0.106294 0.175055 3 16 275 259 >> 345.216 332 0.076795 0.166036 4 16 302 286 >> 285.912 108 0.043888 0.196419 5 16 395 379 >> 303.11 372 0.126033 0.207488 6 16 501 485 >> 323.242 424 0.125972 0.194559 7 16 621 605 >> 345.621 480 0.194155 0.183123 8 16 730 714 >> 356.903 436 0.086678 0.176099 9 16 814 798 >> 354.572 336 0.081567 0.174786 10 16 832 >> 816 326.313 72 0.037431 0.182355 11 16 833 >> 817 297.013 4 0.533326 0.182784 Total time run: >> 11.489068 Total writes made: 833 Write size: >> 4194304 Bandwidth (MB/sec): 290.015 >> >> Stddev Bandwidth: 175.723 Max bandwidth (MB/sec): 480 Min >> bandwidth (MB/sec): 0 Average Latency: 0.220582 Stddev >> Latency: 0.343697 Max latency: 2.85104 Min >> latency: 0.035381 >> >> Our ultimate aim is to replace existing SAN with ceph,but for that >> it should meet minimum 8000 iops.Can any one help me with this,OSD >> are SSD,CPU has good clock speed,backend network is good but still >> we are not able to extract full capability of SSD disks. >> >> >> >> Thanks, > > Hi, i'm new to ceph so, don't consider my words as holy truth. > > It seems that Samsung 840 (so i assume 850) are crappy for ceph : > > MTBF : > http://lists.ceph.com/pipermail/ceph-users-ceph.com/2014-November/044258.html > Bandwidth > :http://lists.ceph.com/pipermail/ceph-users-ceph.com/2014-December/045247.html > > And according to a confirmed user of Ceph/ProxmoX, Samsung SSDs should > be avoided if possible in ceph storage. > > Apart from that, it seems there was an limitation in ceph for the use > of the complete bandwidth available in SSDs; but i think with less > than 1Mb/s you haven't hit this limit. > > I remind you that i'm not a ceph-guru (far from that, indeed), so feel > free to disagree; i'm on the way to improve my knowledge. > > Best regards. > > > > > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1 > > iEYEARECAAYFAlTxp0UACgkQlhqCFkbqHRb5+wCgrXCM3VsnVE6PCbbpOmQXCXbr > 8u0An2BUgZWismSK0PxbwVDOD5+/UWik > =0o0v > -----END PGP SIGNATURE----- _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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