I changed shared_buffers from 10G to 4G , swap usage has almost become nil. # free total used free shared buffers cached Mem: 32871276 24575824 8295452 0 11064 22167324 -/+ buffers/cache: 2397436 30473840 Swap: 4192912 352 4192560 I also observed that there was a huge IO wait and load spike initially which gradually reduced to normal levels. Now things seems to be fine. but real test shall be during business hours. vmstat output: http://pastebin.com/ygu8gUhS the iowait now is very respectable < 10% and CPU is idling most of the time. # vmstat 10 procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------ r b swpd free buff cache si so bi bo in cs us sy id wa st 2 1 352 8482444 11336 22299100 1 0 450 208 0 0 50 6 39 5 0 4 0 352 8393840 11352 22304484 0 0 480 163 9260 12717 32 4 62 3 0 5 1 352 8474788 11360 22308980 0 0 304 445 8295 12358 28 4 67 2 0 3 0 352 8370672 11376 22316676 0 0 648 158 8760 13214 38 4 55 3 0 11 0 352 8193824 11392 22323572 0 0 621 577 8800 13163 37 4 56 3 0 2 0 352 8229012 11408 22326664 0 0 169 405 9588 13696 34 4 61 1 0 6 1 352 8319176 11424 22333144 0 0 559 170 8830 12929 32 4 61 3 0 I shall also try pgtune in a while. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance