On 31/10/2009 4:32 PM, Karen Pease wrote: > Sorry for the delay in responding, and thanks for your help.
By the way, you may also be able to learn some more using the 'blktrace' tool. This gathers low-level data about what processes are performing I/O on your system. # mount -t debugfs none /sys/kernel/debug # btrace /dev/YOUR_DISK eg on my workstation, Pg is busy on /dev/md1 so: # btrace /dev/md1 > 9,1 0 13496 2.514811417 31109 A W 114959520 + 8 <- (252,3) > 31073056 > 9,1 0 13497 2.514811732 31109 Q W 114959520 + 8 [postgres] > 9,1 0 13498 2.514816413 31109 A W 114959528 + 8 <- (252,3) > 31073064 > 9,1 0 13499 2.514816732 31109 Q W 114959528 + 8 [postgres] > 9,1 0 13500 2.514819960 31109 A W 114959536 + 8 <- (252,3) > 31073072 > 9,1 0 13501 2.514820280 31109 Q W 114959536 + 8 [postgres] > 9,1 0 13502 2.514823399 31109 A W 114959544 + 8 <- (252,3) > 31073080 > 9,1 0 13503 2.514823737 31109 Q W 114959544 + 8 [postgres] > 9,1 0 13504 2.514826792 31109 A W 114959552 + 8 <- (252,3) > 31073088 > 9,1 0 13505 2.514827112 31109 Q W 114959552 + 8 [postgres] > 9,1 0 13506 2.514830715 31109 A W 114959560 + 8 <- (252,3) > 31073096 > 9,1 0 13507 2.514831034 31109 Q W 114959560 + 8 [postgres] > 9,1 0 13508 2.514834278 31109 A W 114959568 + 8 <- (252,3) > 31073104 > 9,1 0 13509 2.514834593 31109 Q W 114959568 + 8 [postgres] > 9,1 0 13510 2.514838977 31109 U N [postgres] 0 > 9,1 0 13511 2.515773952 31109 U N [postgres] 0 > 9,1 0 13512 2.515778889 16 U N [kblockd/0] 0 > 9,1 0 13513 2.519146885 31109 U N [postgres] 0 > 9,1 0 13514 2.520511306 31109 U N [postgres] 0 > CPU0 (9,1): > Reads Queued: 1, 4KiB Writes Queued: 6718, > 26872KiB > Read Dispatches: 0, 0KiB Write Dispatches: 0, > 0KiB > Reads Requeued: 0 Writes Requeued: 0 > Reads Completed: 0, 0KiB Writes Completed: 0, > 0KiB > Read Merges: 0, 0KiB Write Merges: 0, > 0KiB > Read depth: 0 Write depth: 0 > IO unplugs: 53 Timer unplugs: 6 (ignore quotes; working around a stuipid Thunderbird limitation) -- Craig Ringer -- Sent via pgsql-bugs mailing list (pgsql-bugs@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-bugs
