On Thursday, July 21, 2016, Mike Christie <mchristi@xxxxxxxxxx> wrote:
On 07/21/2016 11:41 AM, Mike Christie wrote:
> On 07/20/2016 02:20 PM, Jake Young wrote:
>>
>> For starters, STGT doesn't implement VAAI properly and you will need to
>> disable VAAI in ESXi.
>>
>> LIO does seem to implement VAAI properly, but performance is not nearly
>> as good as STGT even with VAAI's benefits. The assumption for the cause
>> is that LIO currently uses kernel rbd mapping and kernel rbd performance
>> is not as good as librbd.
>>
>> I recently did a simple test of creating an 80GB eager zeroed disk with
>> STGT (VAAI disabled, no rbd client cache) and LIO (VAAI enabled) and
>> found that STGT was actually slightly faster.
>>
>> I think we're all holding our breath waiting for LIO librbd support via
>> TCMU, which seems to be right around the corner. That solution will
>
> Is there a thread for that?
Not a thread, but it has come up a few times... Maybe I'm getting ahead of myself. I can't wait for this solution to be available.
>
>> combine the performance benefits of librbd with the more feature-full
>> LIO iSCSI interface. The lrbd configuration tool for LIO from SUSE is
>> pretty cool and it makes configuring LIO easier than STGT.
>>
>
> I wrote a tcmu rbd driver a while back. It is based on gpl2 code, so
> Andy could not take it into tcmu. I attached it here if you want to play
> with it.
>
Here it is attached in patch form built against the current tcmu code.
I have not tested it since March, so if there have been major changes to
the tcmu code there might be issues.
You should only use this for testing. I wrote it up in a night. I have
done very little testing.
It only supports READ, WRITE, DISCARD/UNMAP, TUR, MODE_SENSE/SELECT, and
SYNC_CACHE.
Thanks for this! I was able to patch and compile without errors.
I'm having trouble using it though. Does it require targetcli-fb? This should show up as a "User: rbd" backstore, right?
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