-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Matthew Wakeling Sent: July 30, 2008 8:37 AM To: pgsql-performance@postgresql.org Subject: Re: [PERFORM] Database size Vs performance degradation
On Wed, 30 Jul 2008, Dave North wrote: > Running on HP DL380 w/ 4GB RAM, dual 10K HDDs in RAID 0+1 > Checking the stats, the DB size is around 7.5GB; Doesn't fit in RAM. > ...after the load, the DB size was around 2.7GB Does fit in RAM. > One observation I've made on the DB system is the disk I/O seems > dreadfully slow...we're at around 75% I/O wait sometimes and the read > rates seem quite slow (hdparm says around 2.2MB/sec - 20MB/sec for > un-cached reads). That's incredibly slow in this day and age, especially from 10krpm HDDs. Definitely worth investigating. DN: Yeah, I was thinking the same thing. Unlike the folks here, I'm no performance whiz but it did seem crazy slow. Given the 10K disks, it seems to me there is most likely something on the RAID Array itself that is set sub-optimally. Next thing to look at. However, I think vacuuming more agressively is going to be your best win at the moment. DN: As I just replied to the past (very helpful) chap, I think I need to go see what exactly the vac is vac'ing (autovac that is) because although it's running super frequently, the big question is "is it doing anything" :) Cheers Dave -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
