[Lustre-discuss] user space lustre

[Andreas Dilger]

On May 23, 2008  08:11 +0800, Stuart Midgley wrote:
> Right.  So I am still not clear whether 64GB oss's will be of any benefit.  
> My understanding at the moment is that oss's don't benefit from larger 
> memory, hence we run with 2GB.

Sorry to not be clear - the DMU ARC will allow caching on the OSS node.

> --
> Dr Stuart Midgley
> sdm900 at gmail.com
>
>
>>>
>>
>> The implementation of ZFS is segmented into several major functional
>> units.  The data management unit (DMU) is the bulk of the on-disk
>> structure and is what Lustre will actually interface with for the MDT/OST.
>> The adaptive replacement cache (ARC) is the cache management code and
>> is used to manage manage memory in both userspace and the Solaris kernel.
>>
>> As a result, the userspace servers do not benefit at all from having a
>> duplicate kernel-side cache, like any large database implementation,
>> so we will be avoiding that as best possible.  Initially we were doing
>> O_DIRECT IO, but using async IO (libaio) showed much better performance
>> for the way the ARC submits IO to disk.
>>
>> Cheers, Andreas
>> --
>> Andreas Dilger
>> Sr. Staff Engineer, Lustre Group
>> Sun Microsystems of Canada, Inc.
>>

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.