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Re: RAID card recommendation

From: Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>
To: Jochen Erwied <jochen(at)pgsql-performance(dot)erwied(dot)eu>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: RAID card recommendation
Date: 2009-11-24 20:05:28
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Lists: pgsql-performance
On Tue, Nov 24, 2009 at 12:28 PM, Jochen Erwied
<jochen(at)pgsql-performance(dot)erwied(dot)eu> wrote:
> Since I'm currently looking at upgrading my own database server, maybe some
> of the experts can give a comment on one of the following controllers:
> - Promise Technology Supertrak ES4650 + additional BBU
> - Adaptec RAID 5405 SGL/256 SATA/SAS + additional BBU
> - Adaptec RAID 5405Z SGL/512 SATA/SAS
> My personal favourite currently is the 5405Z, since it does not require
> regular battery replacements and because it has 512MB of cache.

Have you searched the -performance archives for references to them?
I'm not that familiar with Adaptec RAID controllers.  Not requiring a
battery check / replacement is nice.

> Since my server only has room for four disks, I'd choose the following
> one:
> - Seagate Cheetah 15K.6 147GB SAS

We use the older gen 15k.5 and have been very happy with them.
Nowadays it seems the fastest Seagates and Hitachis own the market for
super fast drives.

> Drives would be organized as RAID-0 for fast access, I do not need
> terabytes of storage.

So, you're willing (or forced by economics) to suffer downtime due to
drive failure every so often.

> The database currently is about 150 GB in size (including indexes), the
> main table having a bit less than 1 billion rows (maximum will be about 2
> billion) and getting about 10-20 million updates per day, so update speed
> is critical.

So, assuming this means an 8 hour work day for ~20M rows, you're
looking at around 700 per second.

> Currently the database is running on a mdadm raid-0 with four S-ATA drives
> (7.2k rpm), which was ok when the database was half this size...
> Operating System is Gentoo Linux 2.6.31-r1 on a Fujitsu Siemens Primergy
> 200 S2 (2xXEON @ 1.6 GHz) with 4 GB of RAM (which also would be increased
> to its maximum of 8 GB during the above update)

I'd definitely test the heck out of whatever RAID card you're buying
to make sure it performs well enough.  For some loads and against some
HW RAID cards, SW RAID might be the winner.

Another option might be a JBOD box attached to the machine that holds
12 or so 2.5" 15k like the hitachi ultrastar 147G 2.5" drives.  This
sounds like a problem you need to be able to throw a lot of drives at
at one time.  Is it likely to grow much after this?

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Subject: Re: [PERFORM] Strange performance degradation
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Subject: Re: RAID card recommendation

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