Can you point me to the directions for the kernel mode iscsi backend. I was following these directions
Thanks,
Ryan
On Fri, Oct 25, 2019 at 11:29 AM Mike Christie <mchristi@xxxxxxxxxx> wrote:
On 10/25/2019 09:31 AM, Ryan wrote:
> I'm not seeing the emulate_3pc setting under disks/rbd/diskname when
emulate_3pc is only for kernel based backends. tcmu-runner always has
xcopy on.
> calling info. A google search shows that SUSE Enterprise Storage has it
> available. I thought I had the latest packages, but maybe not. I'm using
> tcmu-runner 1.5.2 and ceph-iscsi 3.3. Almost all of my VMs are currently
> on Nimble iSCSI storage. I've actually tested from both and performance
> is the same. Doing the math off the ceph status does show it using 64K
> blocks in both cases.
>
> Control Values
> - hw_max_sectors .. 1024
> - max_data_area_mb .. 256 (override)
> - osd_op_timeout .. 30
> - qfull_timeout .. 5
>
> On Fri, Oct 25, 2019 at 4:46 AM Maged Mokhtar <mmokhtar@xxxxxxxxxxx
> <mailto:mmokhtar@xxxxxxxxxxx>> wrote:
>
> Actually this may not work if moving from a local datastore to Ceph.
> For iSCSI xcopy, both the source and destination need to be
> accessible by the target such as in moving vms across Ceph
> datastores. So in your case, vmotion will be handled by VMWare data
> mover which uses 64K block sizes.
>
> On 25/10/2019 10:28, Maged Mokhtar wrote:
>>
>> For vmotion speed, check "emulate_3pc" attribute on the LIO
>> target. If 0 (default), VMWare will issue io in 64KB blocks which
>> gives low speed. if set to 1 this will trigger VMWare to use vaai
>> extended copy, which activates LIO's xcopy functionality which
>> uses 512KB block sizes by default. We also bumped the xcopy block
>> size to 4M (rbd object size) which gives around 400 MB/s vmotion
>> speed, the same speed can also be achieved via Veeam backups.
>>
>> /Maged
>>
>> On 25/10/2019 06:47, 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 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
>>>
>>> I'm going to test bonnie++ with an rbd volume mounted directly on
>>> the 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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