I'm trying to get better performance out of exporting RBD volumes via
tgt for iSCSI consumers...
By terrible, I'm getting <5MB/sec reads, <50IOPS. I'm pretty sure neither RBD
or iSCSI themselves are the problems; as the individually perform well.
iSCSI to RAM-backed: >60MB/sec, >500IOPS
iSCSI to SSD-backed: >50MB/sec, >300IOPS
iSCSI to RBD-backed: <5MB/sec, <50IOPS
Cluster:
4 nodes (ceph1..4):
- Supermicro 6027TR-D70RF+ (2U twin systems)
- Chassis A: ceph1, ceph2
- Chassis B: ceph3, ceph4
- 2x E5-2650
- 256GB RAM
- 4x 4TB Seagate ST4000NM0023 SAS, dedicated to Ceph
- 2x 512GB Samsung 840 PRO
- MD RAID1
- LVM
- LV: OS on 'root', 20GiB
- LV: Ceph Journals, 8GB, one per Ceph disk
- 2x Bonded 1GbE network
- 10GbE network:
- port1: to switch
- port2: direct-connect pairs: ceph1/3 ceph2/4 (vertical between chassis)
- All 4 nodes run OSPF
- ceph1/2; ceph3/4: ~9.8Gbit bandwidth confirmed
- ceph1/3; ceph2/4: ~18.2Gbit bandwidth confirmed
- The nodes also co-house VMs with Ganeti, backed onto the SSDs w/ DRBD;
- S3 is the main Ceph use-case, and it works well from the VMs.
Direct performance on the nodes is reasonable good, but it would be nice if the
random performance were better.
# rbd bench-write XXXXX
bench-write io_size 4096 io_threads 16 bytes 1073741824 pattern seq
...
elapsed: 36 ops: 246603 ops/sec: 6681.20 bytes/sec: 29090920.91
# rbd bench-write XXXXX
bench-write io_size 4096 io_threads 16 bytes 1073741824 pattern seq
...
elapsed: 48 ops: 246585 ops/sec: 5070.70 bytes/sec: 22080207.55
# rbd bench-write test.libraries.coop --io-pattern rand
bench-write io_size 4096 io_threads 16 bytes 1073741824 pattern rand
...
elapsed: 324 ops: 246178 ops/sec: 757.74 bytes/sec: 3305000.99
# rbd bench-write test.libraries.coop --io-threads 16 --io-pattern rand
--io-size 32768
bench-write io_size 32768 io_threads 16 bytes 1073741824 pattern rand
...
elapsed: 86 ops: 30141 ops/sec: 347.39 bytes/sec: 12375512.34
Yes I know the data below seems small; I have another older cluster of data
that I still have to merge to this newer hardware.
# ceph -w
cluster 401a58ef-5075-49ec-9615-1c2973624252
health HEALTH_WARN 6 pgs stuck unclean; recovery 8472/241829 objects
degraded (3.503%); mds cluster is degraded; mds ceph1 is laggy
monmap e3: 3 mons at
{ceph1=10.77.10.41:6789/0,ceph2=10.77.10.42:6789/0,ceph4=10.77.10.44:6789/0},
election epoch 11486, quorum 0,1,2 ceph1,ceph2,ceph4
mdsmap e1496661: 1/1/1 up {0=ceph1=up:replay(laggy or crashed)}
osdmap e4323895: 16 osds: 16 up, 16 in
pgmap v14695205: 481 pgs, 17 pools, 186 GB data, 60761 objects
1215 GB used, 58356 GB / 59571 GB avail
8472/241829 objects degraded (3.503%)
6 active
475 active+clean
client io 67503 B/s rd, 7297 B/s wr, 13 op/s
TGT setups:
Target 1: rbd.XXXXXXXXXXX
System information:
Driver: iscsi
State: ready
I_T nexus information:
I_T nexus: 11
Initiator: iqn.1993-08.org.debian:01:6b14da6a48b6 alias:
XXXXXXXXXXXXXXXX
Connection: 0
IP Address: 10.77.110.6
LUN information:
LUN: 0
Type: controller
SCSI ID: IET 00010000
SCSI SN: beaf10
Size: 0 MB, Block size: 1
Online: Yes
Removable media: No
Prevent removal: No
Readonly: No
SWP: No
Thin-provisioning: No
Backing store type: null
Backing store path: None
Backing store flags:
LUN: 1
Type: disk
SCSI ID: IET 00010001
SCSI SN: beaf11
Size: 161061 MB, Block size: 512
Online: Yes
Removable media: No
Prevent removal: No
Readonly: No
SWP: No
Thin-provisioning: No
Backing store type: rbd
Backing store path: XXXXXXXXXXXXXXXXXXXXXXx
Backing store flags:
Account information:
ACL information:
XXXXXXXXXXXXXXXXXXXXXXXXXXXxx
# tgtadm --lld iscsi --mode target --op show --tid 1
MaxRecvDataSegmentLength=8192
HeaderDigest=None
DataDigest=None
InitialR2T=Yes
MaxOutstandingR2T=1
ImmediateData=Yes
FirstBurstLength=65536
MaxBurstLength=262144
DataPDUInOrder=Yes
DataSequenceInOrder=Yes
ErrorRecoveryLevel=0
IFMarker=No
OFMarker=No
DefaultTime2Wait=2
DefaultTime2Retain=20
OFMarkInt=Reject
IFMarkInt=Reject
MaxConnections=1
RDMAExtensions=Yes
TargetRecvDataSegmentLength=262144
InitiatorRecvDataSegmentLength=262144
MaxOutstandingUnexpectedPDUs=0
MaxXmitDataSegmentLength=8192
MaxQueueCmd=128
--
Robin Hugh Johnson
Gentoo Linux: Developer, Infrastructure Lead
E-Mail : [email protected]
GnuPG FP : 11ACBA4F 4778E3F6 E4EDF38E B27B944E 34884E85
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