On Tue, Nov 17, 2009 at 9:54 AM, Brad Nicholson <bnichols@xxxxxxxxxxxxxxx> wrote: > On Tue, 2009-11-17 at 11:36 -0500, Merlin Moncure wrote: >> 2009/11/13 Greg Smith <greg@xxxxxxxxxxxxxxx>: >> > As far as what real-world apps have that profile, I like SSDs for small to >> > medium web applications that have to be responsive, where the user shows up >> > and wants their randomly distributed and uncached data with minimal latency. >> > SSDs can also be used effectively as second-tier targeted storage for things >> > that have a performance-critical but small and random bit as part of a >> > larger design that doesn't have those characteristics; putting indexes on >> > SSD can work out well for example (and there the write durability stuff >> > isn't quite as critical, as you can always drop an index and rebuild if it >> > gets corrupted). >> >> I am right now talking to someone on postgresql irc who is measuring >> 15k iops from x25-e and no data loss following power plug test. I am >> becoming increasingly suspicious that peter's results are not >> representative: given that 90% of bonnie++ seeks are read only, the >> math doesn't add up, and they contradict broadly published tests on >> the internet. Has anybody independently verified the results? > > How many times have the run the plug test? I've read other reports of > people (not on Postgres) losing data on this drive with the write cache > on. When I run the plug test it's on a pgbench that's as big as possible (~4000) and I remove memory if there's a lot in the server so the memory is smaller than the db. I run 100+ concurrent and I set checkoint timeouts to 30 minutes, and make a lots of checkpoint segments (100 or so), and set completion target to 0. Then after about 1/2 checkpoint timeout has passed, I issue a checkpoint from the command line, take a deep breath and pull the cord. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
