Okay and what is your plan now to speed up ?
Would it help to put in multiple P3700 per OSD Node to improve
performance for a single Thread (example Storage VMotion) ?
Regards
Am 21.07.16 um 14:17 schrieb Nick Fisk:
-----Original Message-----
From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] On Behalf Of wr@xxxxxxxx
Sent: 21 July 2016 13:04
To: nick@xxxxxxxxxx; 'Horace Ng' <horace@xxxxxxxxx>
Cc: ceph-users@xxxxxxxxxxxxxx
Subject: Re: Ceph + VMware + Single Thread Performance
Hi,
hmm i think 200 MByte/s is really bad. Is your Cluster in production right now?
It's just been built, not running yet.
So if you start a storage migration you get only 200 MByte/s right?
I wish. My current cluster (not this new one) would storage migrate at ~10-15MB/s. Serial latency is the problem, without being able
to buffer, ESXi waits on an ack for each IO before sending the next. Also it submits the migrations in 64kb chunks, unless you get
VAAI working. I think esxi will try and do them in parallel, which will help as well.
I think it would be awesome if you get 1000 MByte/s
Where is the Bottleneck?
Latency serialisation, without a buffer, you can't drive the devices to 100%. With buffered IO (or high queue depths) I can max out
the journals.
A FIO Test from Sebastien Han give us 400 MByte/s raw performance from the P3700.
https://www.sebastien-han.fr/blog/2014/10/10/ceph-how-to-test-if-your-ssd-is-suitable-as-a-journal-device/
How could it be that the rbd client performance is 50% slower?
Regards
Am 21.07.16 um 12:15 schrieb Nick Fisk:
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 !!
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