On Fri, 2006-02-10 at 16:39, Ragnar wrote: > On Fri, 2006-02-10 at 11:24 +0100, Markus Schaber wrote: > > > For lots non-read-only database workloads, RAID5 is a performance > > killer. Raid 1/0 might be better, or having two mirrors of two disks > > each, the first mirror holding system, swap, and the PostgreSQL WAL > > files, the second one holding the data. > > I was under the impression that it is preferable to keep the WAL on > its own spindles with no other activity there, to take full advantage > of the sequential nature of the WAL writes. > > That would mean one mirror for the WAL, and one for the rest. > This, of course, may sometimes be too much wasted disk space, as the WAL > typically will not use a whole disk, so you might partition this mirror > into a small ext2 filesystem for WAL, and use the rest for files seldom > accessed, such as backups.
Well, on most database servers, the actual access to the OS and swap drives should drop to about zero over time, so this is a workable solution if you've only got enough drives / drive slots for two mirrors. ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
