[lustre-discuss] Can logical volumes used as OST?

[Dilger, Andreas]

On 2016/03/15, 16:36, "lustre-discuss on behalf of Mohr Jr, Richard Frank
(Rick Mohr)" <lustre-discuss-bounces at lists.lustre.org on behalf of
rmohr at utk.edu> wrote:

>
>> On Mar 15, 2016, at 4:18 AM, jeevan.patnaik at wipro.com wrote:
>>  
>> 
>> ³You should create an OST that uses the raw block device and does not
>>use partitioning²
>> 
>> Can we use Logical Volume as OST?
>> 
>> And I also wonder why no partitioned device.
>
>As you mentioned, LVM will work with Lustre.  I believe this
>recommendation was originally intended for performance reasons.  (i.e. -
>If the underlying storage was using RAID, then creating partitions might
>cause data not to align well with the RAID stripes.)  But I could be
>wrong about that.

Your memory is exactly correct.  The DOS partition would misalign all IO
by 512 bytes and cause the RAID to have terrible performance.

LVM can be made to align with the underlying RAID alignment, but it is
worthwhile to verify if you want maximum performance.

Cheers, Andreas
-- 
Andreas Dilger

Lustre Principal Architect
Intel High Performance Data Division