I've had a lot of pain with this, smaller block sizes are even worse. You want to try and minimize latency at every point as there is no buffering happening in the iSCSI stack. This means:- 1. Fast journals (NVME or NVRAM) 2. 10GB or better networking 3. Fast CPU's (Ghz) 4. Fix CPU c-state's to C1 5. Fix CPU's Freq to max Also I can't be sure, but I think there is a metadata update happening with VMFS, particularly if you are using thin VMDK's, this can also be a major bottleneck. For my use case, I've switched over to NFS as it has given much more performance at scale and less headache. For the RADOS Run, here you go (400GB P3700): Total time run: 60.026491 Total writes made: 3104 Write size: 4194304 Object size: 4194304 Bandwidth (MB/sec): 206.842 Stddev Bandwidth: 8.10412 Max bandwidth (MB/sec): 224 Min bandwidth (MB/sec): 180 Average IOPS: 51 Stddev IOPS: 2 Max IOPS: 56 Min IOPS: 45 Average Latency(s): 0.0193366 Stddev Latency(s): 0.00148039 Max latency(s): 0.0377946 Min latency(s): 0.015909 Nick > -----Original Message----- > From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] On Behalf Of Horace > Sent: 21 July 2016 10:26 > To: wr@xxxxxxxx > Cc: ceph-users@xxxxxxxxxxxxxx > Subject: Re: Ceph + VMware + Single Thread Performance > > Hi, > > Same here, I've read some blog saying that vmware will frequently verify the locking on VMFS over iSCSI, hence it will have much > slower performance than NFS (with different locking mechanism). > > Regards, > Horace Ng > > ----- Original Message ----- > From: wr@xxxxxxxx > To: ceph-users@xxxxxxxxxxxxxx > Sent: Thursday, July 21, 2016 5:11:21 PM > Subject: Ceph + VMware + Single Thread Performance > > Hi everyone, > > we see at our cluster relatively slow Single Thread Performance on the iscsi Nodes. > > > Our setup: > > 3 Racks: > > 18x Data Nodes, 3 Mon Nodes, 3 iscsi Gateway Nodes with tgt (rbd cache off). > > 2x Samsung SM863 Enterprise SSD for Journal (3 OSD per SSD) and 6x WD > Red 1TB per Data Node as OSD. > > Replication = 3 > > chooseleaf = 3 type Rack in the crush map > > > We get only ca. 90 MByte/s on the iscsi Gateway Servers with: > > rados bench -p rbd 60 write -b 4M -t 1 > > > If we test with: > > rados bench -p rbd 60 write -b 4M -t 32 > > we get ca. 600 - 700 MByte/s > > > We plan to replace the Samsung SSD with Intel DC P3700 PCIe NVM'e for > the Journal to get better Single Thread Performance. > > Is anyone of you out there who has an Intel P3700 for Journal an can > give me back test results with: > > > rados bench -p rbd 60 write -b 4M -t 1 > > > Thank you very much !! > > Kind Regards !! > > _______________________________________________ > 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 _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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