Just to clarify, it is better to separate the different
performance cases:
1- regular io performance ( iops / throughput ), this should be
good.
2- vmotion within datastores managed by Ceph: this will be good,
as xcopy will be used.
3. vmotion between Ceph datastore and an external datastore..this
will be bad. This seems the case you are testing. It is bad
because between 2 different storage systems (iqns are served on
different targets), vaai xcopy cannot be used and vmware does its
own stuff. It moves data using 64k block size, which gives low
performance...to add some flavor, it does indeed use 32 threads,
but unfortunately they use co-located addresses which does not
work well in Ceph as they are hitting the same rbd object, which
gets serialized due to pg locks, so you will not get any
palatalization. Your speed will mostly be determined by a serial
64k, so with 1 ms write latency for ssd cluster, you will get
around 64 MB/s..it will be slightly higher as the extra threads
have some low effect.
Note your esxtop does show 32 active ios under ACTV, the QUED of
zero does is not the queue depth, but rather the "queued" io the
ESX would suspend in case your active reaches the maximum by
adapater ( 128 ).
This is just to clarify, if case 3 is not your primary concern
than i would forget about it and benchmark 1 and 2 if they are
relevant. Else, if 3 is important, i am not sure you can do much
as it is happening within vmware..maybe there could be a way to
map the external iqn to be served by the same target serving the
Ceph iqn then there could be a chance the xcopy could be
activated..Mike would probably know if this has any chance of
working :)
/Maged
On 25/10/2019 22:01, Ryan wrote:
esxtop is showing a queue length of 0
Storage motion to ceph
DEVICE PATH/WORLD/PARTITION
DQLEN WQLEN ACTV QUED %USD LOAD CMDS/s READS/s WRITES/s
MBREAD/s MBWRTN/s DAVG/cmd KAVG/cmd GAVG/cmd QAVG/cmd
naa.6001405ec60d8b82342404d929fbbd03 -
128 - 32 0 25 0.25 1442.32 0.18 1440.50
0.00 89.78 21.32 0.01 21.34 0.01
Storage motion from ceph
DEVICE PATH/WORLD/PARTITION
DQLEN WQLEN ACTV QUED %USD LOAD CMDS/s READS/s WRITES/s
MBREAD/s MBWRTN/s DAVG/cmd KAVG/cmd GAVG/cmd QAVG/cmd
naa.6001405ec60d8b82342404d929fbbd03 -
128 - 32 0 25 0.25 4065.38 4064.83 0.36
253.52 0.00 7.57 0.01 7.58 0.00
I tried using fio like you mentioned but it was hanging with
[r=0KiB/s,w=0KiB/s][r=0,w=0 IOPS] and the ETA kept climbing. I
ended up using rbd bench on the ceph iscsi gateway. With a 64K
write workload I'm seeing 400MB/s transfers.
rbd create test --size 100G --image-feature layering
rbd map test
mkfs.ext4 /dev/rbd/rbd/test
mount /dev/rbd/rbd/test test
rbd create testec --size 100G --image-feature layering
--data-pool rbd_ec
rbd map testec
mkfs.ext4 /dev/rbd/rbd/testec
mount /dev/rbd/rbd/testec testec
[root@ceph-iscsi1 mnt]# rbd bench --image test --io-size 64K
--io-type write --io-total 10G
bench type write io_size 65536 io_threads 16 bytes
10737418240 pattern sequential
SEC OPS OPS/SEC BYTES/SEC
1 6368 6377.59 417961796.64
2 12928 6462.27 423511630.71
3 19296 6420.18 420752986.78
4 26320 6585.61 431594792.67
5 33296 6662.37 436624891.04
6 40128 6754.67 442673957.25
7 46784 6765.75 443400452.26
8 53280 6809.02 446236110.93
9 60032 6739.67 441691068.73
10 66784 6698.91 439019550.77
11 73616 6690.88 438493253.66
12 80016 6654.35 436099640.00
13 85712 6485.07 425005611.11
14 91088 6202.49 406486113.46
15 96896 6021.17 394603137.62
16 102368 5741.19 376254347.24
17 107568 5501.57 360550910.38
18 113728 5603.17 367209502.58
19 120144 5820.48 381451245.32
20 126496 5917.60 387816078.53
21 132768 6089.71 399095466.00
22 139040 6306.98 413334431.09
23 145104 6276.42 411331743.63
24 151440 6256.67 410036891.68
25 157808 6261.12 410328554.98
26 163456 6140.03 402392725.36
elapsed: 26 ops: 163840 ops/sec: 6271.36 bytes/sec:
410999626.38
[root@ceph-iscsi1 mnt]# rbd bench --image testec --io-size 64K
--io-type write --io-total 10G
bench type write io_size 65536 io_threads 16 bytes
10737418240 pattern sequential
SEC OPS OPS/SEC BYTES/SEC
1 7392 7415.38 485974266.41
2 14464 7243.59 474715656.29
3 22000 7341.08 481104853.50
4 29408 7352.29 481839517.16
5 37296 7459.38 488857889.75
6 44864 7494.36 491150574.57
7 52848 7676.76 503104281.98
8 60784 7756.76 508347136.11
9 68608 7835.26 513491609.52
10 76784 7902.30 517885290.67
11 84544 7935.96 520091129.45
12 92432 7916.76 518832844.57
13 100064 7855.96 514848275.43
14 107040 7692.52 504136734.09
15 114320 7499.66 491497933.56
16 121744 7436.99 487390477.85
17 129664 7438.92 487517345.01
18 136704 7326.50 480149408.39
19 144960 7587.00 497221460.09
20 153264 7796.56 510955233.33
21 160832 7814.44 512126854.90
elapsed: 21 ops: 163840 ops/sec: 7659.97 bytes/sec:
502004079.43
On 10/24/2019 11:47 PM,
Ryan wrote:
> I'm using CentOS 7.7.1908 with kernel
3.10.0-1062.1.2.el7.x86_64. The
> workload was a VMware Storage Motion from a local SSD
backed datastore
Ignore my comments. I thought you were just doing fio like
tests in the vm.
> to the ceph backed datastore. Performance was measured
using dstat on
> the iscsi gateway for network traffic and ceph status
as this cluster is
> basically idle. I changed max_data_area_mb to 256 and
cmdsn_depth to
> 128. This appears to have given a slight improvement of
maybe 10MB/s.
>
> Moving VM to the ceph backed datastore
> io:
> client: 124 KiB/s rd, 76 MiB/s wr, 95 op/s rd,
1.26k op/s wr
>
> Moving VM off the ceph backed datastore
> io:
> client: 344 MiB/s rd, 625 KiB/s wr, 5.54k op/s
rd, 62 op/s wr
>
If you run esxtop while running your test what do you see
for the number
of commands in the iscsi LUN's queue?
> I'm going to test bonnie++ with an rbd volume mounted
directly on the
To try and isolate if its the iscsi or rbd, you need to run
fio with the
librbd io engine. We know krbd is going to be the fastest.
ceph-iscsi
uses librbd so it is a better baseline. If you are not
familiar with fio
you can just do something like:
fio --group_reporting --ioengine=rbd --direct=1
--name=librbdtest
--numjobs=32 --bs=512k --iodepth=128 --size=10G --rw=write
--rbd=name_of_your_image -pool=name_of_pool
> iscsi gateway. Also will test bonnie++ inside a VM on a
ceph backed
> datastore.
>
> On Thu, Oct 24, 2019 at 7:15 PM Mike Christie <mchristi@xxxxxxxxxx
> <mailto:mchristi@xxxxxxxxxx>>
wrote:
>
> On 10/24/2019 12:22 PM, Ryan wrote:
> > I'm in the process of testing the iscsi target
feature of ceph. The
> > cluster is running ceph 14.2.4 and ceph-iscsi
3.3. It consists of 5
>
> What kernel are you using?
>
> > hosts with 12 SSD OSDs per host. Some basic
testing moving VMs to
> a ceph
> > backed datastore is only showing 60MB/s
transfers. However moving
> these
> > back off the datastore is fast at 200-300MB/s.
>
> What is the workload and what are you using to
measure the throughput?
>
> If you are using fio, what arguments are you using?
And, could you
> change the ioengine to rbd and re-run the test from
the target system so
> we can check if rbd is slow or iscsi?
>
> For small IOs, 60 is about right.
>
> For 128-512K IOs you should be able to get around
300 MB/s for writes
> and 600 for reads.
>
> 1. Increase max_data_area_mb. This is a kernel
buffer lio/tcmu uses to
> pass data between the kernel and tcmu-runner. The
default is only 8MB.
>
> In gwcli cd to your disk and do:
>
> # reconfigure max_data_area_mb %N
>
> where N is between 8 and 2048 MBs.
>
> 2. The Linux kernel target only allows 64 commands
per iscsi session by
> default. We increase that to 128, but you can
increase this to 512.
>
> In gwcli cd to the target dir and do
>
> reconfigure cmdsn_depth 512
>
> 3. I think ceph-iscsi and lio work better with
higher queue depths so if
> you are using fio you want higher numjobs and/or
iodepths.
>
> >
> > What should I be looking at to track down the
write performance issue?
> > In comparison with the Nimble Storage arrays I
can see 200-300MB/s in
> > both directions.
> >
> > Thanks,
> > Ryan
> >
> >
> >
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