Re: Performance advice for a new low(er)-power server

On Thu, Jun 16, 2011 at 1:43 PM, Greg Smith <greg(at)2ndquadrant(dot)com> wrote:
> These drives are one of the worst choices on the market for PostgreSQL
> storage.  They're unusably slow if you disable the caches, and even that
> isn't guaranteed to work.  There is no way to make them safe.  See
> http://wiki.postgresql.org/wiki/Reliable_Writes for more details.  The 3rd
> generation SSDs from Intel are much, much better; see
> http://blog.2ndquadrant.com/en/2011/04/intel-ssd-now-off-the-sherr-sh.html
> for details.

I don't necessarily agree. the drives are SLC and have the potential
to have a much longer lifespan than any MLC drive, although this is
going to depend a lot on the raid controller if write caching is
disabled. Also, reading the post that got all this started
(http://www.mysqlperformanceblog.com/2009/03/02/ssd-xfs-lvm-fsync-write-cache-barrier-and-lost-transactions/)
the OP was able to configure them to run durably with 1200 write iops.
While not great, that's still much better than any spinning disk.

So, if drive lifespan is a big deal, I think they still technically
have a place *today) although the drives that are just about to come
out (the 710 and 720) will make them obsolete, because the built in
caching (particularly for the SLC 720) will make the drive superior in
every respect.

merlin