[Lustre-discuss] Clarification on DDN performance best practices

[Mag Gam]

Kit:

Thanks for the reply. I was under the impression you create your own
version of Lustre and then sell it as a "blackbox" to the customers.

I think Terascala does this, and I would like to figure out exactly
what they include in their Lustre offering.

TIA

On Wed, Apr 15, 2009 at 11:37 PM, Kit Westneat <kwestneat at ddn.com> wrote:
> Our storage systems just present as scsi devices either using fc or ib srp. When we do Lustre installations, we just use whatever is most stable. Most recently we have been doing a lot of rhel5 based installs, so just use the sun provided rhel5 lustre kernel.
>
> - Kit
>
> ----- Original Message -----
> From: Mag Gam <magawake at gmail.com>
> To: Kit Westneat
> Cc: Peter Grandi <pg_lus at lus.for.sabi.co.uk>; List Lustre discussion <lustre-discuss at lists.lustre.org>
> Sent: Wed Apr 15 20:11:41 2009
> Subject: Re: [Lustre-discuss] Clarification on DDN performance best practices
>
> What kernel does DDN use for its products? Or is that a closed secret?
>
>
> On Mon, Apr 13, 2009 at 10:17 AM, Kit Westneat <kwestneat at ddn.com> wrote:
>>
>>> As to this, the tier are organized as something similar to 8+2 RAID6.
>>> For 8-way data, which is the unit? Sectors? Blocks? In other words, what
>>> is the stripe data size in KiB with a sector size of 512 vs. a sector
>>> size of 4KiB?
>>>
>> The S2A directRAID6 is actually based on RAID3, so we use byte striping
>> instead of block striping. The 4k alignment comes from the physical disk
>> sector size of 512-bytes (512 * 8 = 4k). The S2A has a cache segment
>> size, which while independent of the LUN sector size, is sort of similar
>> in some ways to a block size on a RAID5, though it will never do a
>> read-modify-write. The cache size can be set between 128k - 2M, and for
>> Lustre, we usually set it to 1 or 2M, since Lustre currently operates
>> with 1M messages.
>>
>> This picture sort of describes from a high level what happens on the
>> data path (the text is very marketing heavy unfortunately):
>> http://ddn.com/index.php?id=48
>>
>> If you are going to be at LUG, DDN will have a fair number folks
>> including myself there, feel free to come say hi. We'll also be talking
>> at 1 on Friday.
>>
>> HTH,
>> Kit
>>
>> --
>> ---
>> Kit Westneat
>> kwestneat at datadirectnet.com
>> 812-484-8485
>>
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>> http://lists.lustre.org/mailman/listinfo/lustre-discuss
>>
>