Re: SSDs with Postgresql?

On 2011-04-19 19:07, Benjamin Smith wrote:
>
> On Sunday, April 17, 2011 01:55:02 AM Henry C. wrote:
>
> >
>
> > Exactly. Be aware of the risks, plan for failure and reap the rewards.
>
>
> Just curious what your thoughts are with respect to buying SSDs and
> mirroring them with software RAID 1. (I use Linux/CentOS)
>

Since SSD fail when the write cycles are gone, it wouldn't make sense to
buy two identical ones and put them in a RAID 1: under normal
circumstances they'd fail simultanously. An idea I'm thinking of is to
put both a OCZ Vertex 2 Pro and Intel 320 in a software RAID 1 setup. It
would have the benefit that there are no complications to be expected
with an extra device layer from a hardware RAID card, such as
incompatibilites between controller and SSD firmware, or not being able
to access the physical disk's smart values, which in the SSD case are
important to figure out the remaining lifetime. Also since both drives
have a supercap, PostgreSQL data on it would survive power failures. It
would be interesting if md could be configured to do reads on both
mirror legs and compare them before returning values, like a continual
check, but there doesn't seem to be a option for something like that.

--
Yeb Havinga
http://www.mgrid.net/
Mastering Medical Data