CEPH ISCSI Gateway - very slow performance - Fine tuning help

[Chan]

Hello

I am having few severe performance issues on my ceph cluster.

Scenario 1 )    When I mount a rbd volume directly using rbd map command to a linux kernel. I am getting good performance.

when I do dd on the above volume, I am getting 380 - 430 MB's. -- I am good with this.

Scenario 2 ) I am using iscsi-gateway. iscsi1 and iscs2 as targets and presenting LUNS ro all my initiators.

When I do dd on the volumes presented via iscsi gateway, my performance is 10 to 25 MB's. which is very poor.

I am gwcli commandline and connot use the belwo command

"create images image=test1 size=100g max_data_area_mb=128"

' Unexpected keyword error '

[ASVINCHANDAR SELVARAJ]

I tried this 

Centos 7.4 

echo '4096000' > /sys/block/sdb/queue/max_sectors_kb 

But I am getting Input/output error 

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[Ulrich Windl]

>>> ASVINCHANDAR SELVARAJ <asvinc...@gmail.com> schrieb am 14.02.2019 um 06:03
in Nachricht
<CAGuzt4m-X7Ps0OHZpor0w1u-...@mail.gmail.com>:

> I tried this
>
> Centos 7.4
>
> echo '4096000' > /sys/block/sdb/queue/max_sectors_kb
>
> But I am getting Input/output error

Actually for FC SAN storage we made the opposite experience: Some filesystems like ext3 occasionally make bug requests (like 1000 sectors), and such big requests slow down the SAN storage. We use values significantly below 128kB.

I'd recommend to do analysis before doing tuning, or do an automated tuning test to find out which values give the best performance in your scenario. You could also use tools like iftop or iotop to monitor local and remote I/O.

Regards,
Ulrich

[Ulrich Windl]

>>> "Ulrich Windl" <Ulrich...@rz.uni-regensburg.de> schrieb am 14.02.2019 um
09:05 in Nachricht <5C6521330200...@gwsmtp1.uni-regensburg.de>:

> filesystems like ext3 occasionally make bug requests (like 1000 sectors), and

Sorry: s/bug/big/