On Tue, Dec 11, 2012 at 10:48 AM, Bruce Momjian <bruce@xxxxxxxxxx> wrote: > On Mon, Dec 10, 2012 at 02:05:09AM -0500, Greg Smith wrote: >> On 11/14/12 2:11 AM, Toby Corkindale wrote: >> >So on the face of it, I think the Sandforce-based drives are probably a >> >winner here, so I should look at the Intel 520s for evaluation, and >> >whatever the enterprise equivalent are for production. >> >> As far as I know the 520 series drives fail the requirements >> outlined at http://wiki.postgresql.org/wiki/Reliable_Writes and you >> can expect occasional data corruption after a crash when using them. >> As such, any performance results you get back are fake. You can't >> trust the same results will come back from their drives that do >> handle writes correctly. I'm not aware of any SSD with one of these >> compressing Sandforce controller that's on the market right now that >> does this correctly; they're all broken for database use. The quick >> rule of thumb is that if the manufacturer doesn't brag about the >> capacitors on the drive, it doesn't have any and isn't reliable for >> PostgreSQL. >> >> The safe Intel SSD models state very clearly in the specifications >> how they write data in case of a crash. The data sheet for the 320 >> series drives for example says "To reduce potential data loss, the >> Intel® SSD 320 Series also detects and protects from unexpected >> system power loss by saving all cached data in the process of being >> written before shutting down". The other model I've deployed and >> know is safe are the 710 series models, which are the same basic >> drive but with different quality flash and tuning for longevity. >> See http://blog.2ndquadrant.com/intel_ssds_lifetime_and_the_32/ for >> details. The 710 series drives are quite a bit more expensive than >> Intel's other models. > > It looks like the newer Intel 330 SSD also lacks a capacitor. I believe that's the case. The only choices today are the 320, 710, and the upcoming DC S3700 (which looks explicitly designed for database use). merlin -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
