Re: Opinions on SSDs

On 08/12/2013 08:28 AM, David F. Skoll wrote:
>
> Hi,
>
> We run a fairly write-intensive workload and are looking at upgrading
> our Pg servers.  (PostgreSQL 9.1; no practical way to upgrade to 9.2 for
> a while because we use what's packaged with Debian.)

apt.postgresql.org

>
> I'm considering the following configuration:
>
>     Dual 4-core Intel CPU (E5620 at 2.4GHz)
>
>     192GB of RAM
>
>     Sixteen 240GB Intel SSD 520 series drives arranged using Linux
>     RAID-10.  The RAID 10 array will use eight mirrored stripes using the
>     "offset-copies" RAID10 scheme.
>
> Questions:
>
> 1) Has anyone had experience with Intel 520 SSDs?  Are they reliable?
> When they fail, do they fail nicely (ie, failure detected and bad drive
> removed from RAID array) or horribly (data silently corrupted...) ?

I don't recall if the 520s have powerloss protection but you will want
to check that.

>
> 2) Is this RAID arrangement sensible?  I've seen reports where some
> people keep the pg_xlog directory on a separate RAID array, but I
> don't really see the advantage with SSDs.

Put the pg_xlog on spindles, they are more than fast enough and won't
eat up the write life of your SSDs.

JD


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