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Re: SSD + RAID

From: Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>
To: Laszlo Nagy <gandalf(at)shopzeus(dot)com>
Cc: pgsql-performance <pgsql-performance(at)postgresql(dot)org>
Subject: Re: SSD + RAID
Date: 2009-11-13 14:48:05
Message-ID: dcc563d10911130648r17c96406s9999119ebd963b96@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
2009/11/13 Laszlo Nagy <gandalf(at)shopzeus(dot)com>:
> Hello,
>
> I'm about to buy SSD drive(s) for a database. For decision making, I used
> this tech report:
>
> http://techreport.com/articles.x/16255/9
> http://techreport.com/articles.x/16255/10
>
> Here are my concerns:
>
>   * I need at least 32GB disk space. So DRAM based SSD is not a real
>     option. I would have to buy 8x4GB memory, costs a fortune. And
>     then it would still not have redundancy.
>   * I could buy two X25-E drives and have 32GB disk space, and some
>     redundancy. This would cost about $1600, not counting the RAID
>     controller. It is on the edge.

I'm not sure a RAID controller brings much of anything to the table with SSDs.

>   * I could also buy many cheaper MLC SSD drives. They cost about
>     $140. So even with 10 drives, I'm at $1400. I could put them in
>     RAID6, have much more disk space (256GB), high redundancy and

I think RAID6 is gonna reduce the throughput due to overhead to
something far less than what a software RAID-10 would achieve.

>     POSSIBLY good read/write speed. Of course then I need to buy a
>     good RAID controller.

I'm guessing that if you spent whatever money you were gonna spend on
more SSDs you'd come out ahead, assuming you had somewhere to put
them.

> My question is about the last option. Are there any good RAID cards that are
> optimized (or can be optimized) for SSD drives? Do any of you have
> experience in using many cheaper SSD drives? Is it a bad idea?

This I don't know.  Some quick googling shows the Areca 1680ix and
Adaptec 5 Series to be able to handle Samsun SSDs.

In response to

  • SSD + RAID at 2009-11-13 12:46:15 from Laszlo Nagy

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