Extreme slowness in SSD cluster with 3 nodes and 9 OSD with 3.16-3 kernel

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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,
_______________________________________________
ceph-users mailing list
ceph-users@xxxxxxxxxxxxxx
http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com




[Index of Archives]     [Information on CEPH]     [Linux Filesystem Development]     [Ceph Development]     [Ceph Large]     [Ceph Dev]     [Linux USB Development]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [xfs]


  Powered by Linux