Re: Opinions on SSDs

On Mon, Aug 12, 2013 at 08:33:04AM -0700, Joshua D. Drake wrote:
> >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.

I am pretty sure they don't. The only options are the Intel 320 and
710, I think. Here is a blog about it:

http://blog.2ndquadrant.com/intel_ssds_lifetime_and_the_32/

Look for "Enhanced Power Loss Data Protection". Intel does not make it
easy to find all drive that have it --- you have to look at each spec
sheet.

> >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.

Given its small size and need for fast fsync, I have WAL on SSDs, and
the data on magnetic disk. You are right the WAL can generate a lot of
writes, but just use smartctl monitoring and replace the SSD when
needed.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ It's impossible for everything to be true. +