[openstack-dev] [cinder][sahara] LVM vs BDD drivers performance tests results

Duncan Thomas duncan.thomas at gmail.com
Mon Sep 19 20:54:23 UTC 2016


I think there's some mileage in some further work on adding local LVM,
since things like striping/mirroring for performace can be done. We can
prototype it and get the numbers before even thinking about merging though
- as additions to an already fully featured driver. these seem more
worthwhile a way forward than limping on with the bdd driver.

Moving to change our default target to LIO seems worthwhile - I'd suggest
being cautious with deprecation rather than aggressive though - aiming to
change the default in 'O' then planning the rest based on how that goes.

On 19 September 2016 at 21:54, John Griffith <john.griffith8 at gmail.com>
wrote:

>
>
> On Mon, Sep 19, 2016 at 12:01 PM, Ivan Kolodyazhny <e0ne at e0ne.info> wrote:
>
>> + [sahara] because they are primary consumer of the BDD.
>>
>> John,
>> Thanks for the answer. My comments are inline.
>>
>> Regards,
>> Ivan Kolodyazhny,
>> http://blog.e0ne.info/
>>
>> On Mon, Sep 19, 2016 at 4:41 PM, John Griffith <john.griffith8 at gmail.com>
>> wrote:
>>
>>>
>>>
>>> On Mon, Sep 19, 2016 at 4:43 AM, Ivan Kolodyazhny <e0ne at e0ne.info>
>>> wrote:
>>>
>>>> Hi team,
>>>>
>>>> We did some performance tests [1] for LVM and BDD drivers. All tests
>>>> were executed on real hardware with OpenStack Mitaka release.
>>>> Unfortunately, we didn't have enough time to execute all tests and compare
>>>> results. We used Sahara/Hadoop cluster with TestDFSIO and others
>>>> tests.
>>>>
>>>> All tests were executed on the same hardware and OpenStack release.
>>>> Only difference were in cinder.conf to enable needed backend and/or target
>>>> driver.
>>>>
>>>> Tests were executed on following configurations:
>>>>
>>>>    - LVM +TGT target
>>>>    - LVM+LocalTarget: PoC based on [2] spec
>>>>    - LVM+LIO
>>>>    - Block Device Driver.
>>>>
>>>>
>>>> Feel free to ask question if any about our testing infrastructure,
>>>> environment, etc.
>>>>
>>>>
>>>> [1] https://docs.google.com/spreadsheets/d/1qS_ClylqdbtbrVSvwbbD
>>>> pdWNf2lZPR_ndtW6n54GJX0/edit?usp=sharing
>>>> [2] https://review.openstack.org/#/c/247880/
>>>>
>>>> Regards,
>>>> Ivan Kolodyazhny,
>>>> http://blog.e0ne.info/
>>>>
>>>> ____________________________________________________________
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>>>>
>>>> ​Thanks Ivan, so I'd like to propose we (the Cinder team) discuss a few
>>> things (again):
>>>
>>> 1. Deprecate the BDD driver
>>>  Based on the data here LVM+LIO the delta in performance ​(with the
>>> exception of the Terravalidate run against 3TB) doesn't seem significant
>>> enough to warrant maintaining an additional driver that has only a subset
>>> of features implemented.  It would be good to understand why that
>>> particular test has such a significant peformance gap.
>>>
>> What about Local Target? Does it make sense to implement it instead BDD?
>>
> ​Maybe I'm missing something, what would the advantage be?  LVM+LIO and
> LVM+LOCAL-TARGET seem pretty close.  In the interest of simplicity and
> maintenance just thinking maybe it would be worth considering just using
> LVM+LIO across the board.
>>
>
>>
>>> 2. Consider getting buy off to move the default implementation to use
>>> the LIO driver and consider deprecating the TGT driver
>>>
>> +1. Let's bring this topic for the next weekly meeting.
>>
>>
>>
>>>
>>> I realize this probably isn't a sufficient enough data set to make those
>>> two decisions but I think it's at least enough to have a more informed
>>> discussion this time.
>>>
>>> Thanks,
>>> John​
>>>
>>>
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>>>
>>
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-- 
-- 
Duncan Thomas
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