Hi Richard, Thank for your prompt reply. I have used the command "vmstat 10" to investigate the I/O issue and listed below :
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 0 26848 8376 2208 595796 0 0 16 16 14 13 5 2 91 2 1 0 26848 8024 2128 596324 0 0 1595 620 2006 3489 45 7 39 9 2 0 26848 8432 2024 595988 0 0 1399 163 1953 3830 38 8 47 7 2 0 26936 8488 2008 596092 0 0 1696 636 1973 7423 52 8 31 9 1 0 26936 8476 2008 596148 0 0 1237 660 1618 1863 34 6 50 11 <-- The starting time when the pgsql log transaction due to long execution duration. 0 0 26936 8024 1980 596756 0 0 1983 228 1985 2241 52 8 31 10 0 2 26936 8312 2040 595904 0 0 405 16674 1449 1675 17 6 1 76 <-- The intermediate time reaching I/O peak. 0 0 26936 8544 2088 594964 0 0 1191 8295 680 1038 30 4 13 53 2 0 26936 8368 2124 595032 0 0 517 935 866 985 14 3 79 4 0 0 26936 8368 2064 595228 0 0 1706 190 1979 2356 45 7 38 9 0 0 26936 8196 2132 595452 0 0 1713 642 1913 2238 44 8 37 11 1 1 26936 8164 2168 595512 0 0 1652 666 2011 2542 45 7 38 10 0 1 26936 8840 2160 594592 0 0 1524 228 1846 2116 42 8 43 7 0 0 26936 7384 2200 596304 0 0 1584 604 1972 2137 41 7 40 11 As you said, it seems for each 3~4 minutes, there is a I/O peak. But what is the problem indicating by it ? Thanks for help. Twinsen 2007/6/28, Richard Huxton <[EMAIL PROTECTED]>:
Ho Fat Tsang wrote: > Hi Richard, > > I have tuned the checkpoint_timeout to 30 second which is ten times less > than default and the issue is still reproduced. Do you have any recommended > configuration for WAL ? If you look at the output of "vmstat 10" and "iostat -m 10" (I'm assuming you're on Linux) does it show your I/O peaking every three minutes? I might have been wrong about the cause. -- Richard Huxton Archonet Ltd
