On Sat, 2003-09-13 at 23:44, Cott Lang wrote: > > Having WAL on a separate drive from the database would be something of > > a win. I'd buy that 1 disk for OS+WAL and then RAID [something] > > across the other two drives for the database would be pretty helpful. > > Just my .02, > > I did a lot of testing before I deployed our ~50GB postgresql databases > with various combinations of 6 15k SCSI drives. I did custom benchmarks > to simulate our applications, I downloaded several benchmarks, etc. > > It might be a fluke, but I never got better performance with WALs on a > different disk than I did with all 6 disks in a 0+1 configuration. > Obviously that's not an option with 3 disks. =)
Interesting. Where did you put the OS, and what kind of, and how many, SCSI controllers did you have? PCI 32bit/33MHz or 64bit/66MHz PCI? 32bit/33MHz PCI has a max throughput of 132MB/s, which is 60% smaller than the theoretical bandwidth of U320 SCSI, so maybe you were saturating the PCI bus, and that's why a separate WAL didn't show any improvement? (If the WAL ever becomes the vehicle for PITR, then it will have to be on a separate disk [and preferably a separate controller], even if it slows performance.) -- ----------------------------------------------------------------- Ron Johnson, Jr. [EMAIL PROTECTED] Jefferson, LA USA "Eternal vigilance is the price of liberty: power is ever stealing from the many to the few. The manna of popular liberty must be gathered each day, or it is rotten... The hand entrusted with power becomes, either from human depravity or esprit de corps, the necessary enemy of the people. Only by continual oversight can the democrat in office be prevented from hardening into a despot: only by unintermitted agitation can a people be kept sufficiently awake to principle not to let liberty be smothered in material prosperity... Never look, for an age when the people can be quiet and safe. At such times despotism, like a shrouding mist, steals over the mirror of Freedom" Wendell Phillips ---------------------------(end of broadcast)--------------------------- TIP 7: don't forget to increase your free space map settings
