Re: raid10 write performance

From: Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>
To: Ivan Voras <ivoras(at)freebsd(dot)org>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: raid10 write performance
Date: 2010-06-23 12:56:39
Message-ID: AANLkTik1U496rcnyT-uvIWayxescnZ406h0fW1trGMc7@mail.gmail.com
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On Wed, Jun 23, 2010 at 6:06 AM, Ivan Voras <ivoras(at)freebsd(dot)org> wrote:
> On 06/22/10 16:40, Greg Smith wrote:
>> Grzegorz Jaśkiewicz wrote:
>>> raid: serveRAID M5014 SAS/SATA controller
>>>
>>
>> Do the "performant servers" have a different RAID card?  This one has
>> terrible performance, and could alone be the source of your issue.  The
>> ServeRAID cards are slow in general, and certainly slow running RAID10.
>
> What are some good RAID10 cards nowadays?

LSI, Areca, 3Ware (now LSI I believe)

> On the other hand, RAID10 is simple enough that soft-RAID
> implementations should be more than adequate - any ideas why a dedicated
> card has it "slow"?

This is mostly a problem with some older cards that focused on RAID-5
performance, and RAID-10 was an afterthought. On many of these cards
(older PERCs for instance) it was faster to either use a bunch of
RAID-1 pairs in hardware with RAID-0 in software on top, or put the
thing into JBOD mode and do it all in software.

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