[Jim C. Nasby - Thu at 11:31:26AM -0500] > The issue with pg_xlog is you don't need bandwidth... you need super-low > latency. The best way to accomplish that is to get a battery-backed RAID > controller that you can enable write caching on. In fact, if the > controller is good enough, you can theoretically get away with just > building one big RAID10 and letting the controller provide the > low-latency fsyncs that pg_xlog depends on. I was talking a bit about our system administrator. We're running 4 disks in raid 1+0 for the database and 2 disks in raid 1 for the WALs and for OS. He wasn't really sure if we had write cacheing on the RAID controller or not. He pasted me some lines from the dmesg: sda: asking for cache data failed sda: assuming drive cache: write through failed line is expected from these controllers 0000:02:0e.0 RAID bus controller: Dell PowerEdge Expandable RAID controller 4 (rev 06) I think we're going to move system logs, temporary files and backup files from the wal-disks to the db-disks. Since our database aren't on fire for the moment, I suppose we'll wait moving the rest of the OS :-)
