Folks, First, cc'ing Greg Smith to see if he can address this with the Fusion folks so that they stop giving out a bad guide. On 06/20/2013 01:13 PM, Shaun Thomas wrote: > On 06/20/2013 02:56 PM, CS DBA wrote: > >> They have a PostgreSQL setup guide from Fusion recommending the >> following settings: >> effective_io_concurrency=0 >> bgwriter_lru_maxpages=0 >> random_page_cost=0.1 >> sequential_page_cost=0.1 > > Well, since FusionIO drives have a limited write cycle (5PB?), I can > somewhat see why they would recommend turning off the background writer. > We were a bit more conservative in our settings, though: > > seq_page_cost = 1.0 # Default > random_page_cost = 1.0 # Reduce to match seq_page_cost > > Yep. That's it. Just the one setting. FusionIO drives are fast, but > they're not infinitely fast. My tests (and others) show they're about > 1/2 the speed of memory, regarding IOPS. And while they can serve very > aggressive sequential reads, they're not orders of magnitude faster than > spindles in anything but IOPS. > > Knowing that, we reduced random page fetches to be the same speed as > sequential page fetches. This has served our heavy OLTP system (and its > FusionIO underpinnings) very well so far. Did you compare setting RPC to 1.0 vs. setting it to 1.1, or something else just slightly higher than SPC? -- Josh Berkus PostgreSQL Experts Inc. http://pgexperts.com -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
