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vmstat example
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| vmstat is a helpful tool for figuring out performance problems on servers. | |
| user@server-prod-db01:~$ vmstat 5 | |
| procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- | |
| r b swpd free buff cache si so bi bo in cs us sy id wa | |
| 1 0 10860 51884 41656 3712392 0 0 1297 107 0 0 10 3 84 3 | |
| 0 0 10860 50388 41668 3713204 0 0 41 446 1409 1173 6 2 91 1 | |
| The "b" column shows blocked processes waiting for IO. In this case it's 0, which is a good thing. | |
| "si" and "so" show blocks into and out of swap, again this looks good since both are 0 and we | |
| don't want any swap activity on the db server. Other things to look for are high "cs" counts | |
| (context switches) or lots of input/output activity which can cause the system to be slow. |
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Previously this system frequently had positive numbers in "b" (blocked processes), and database tuning fixed this issue. Specifically, we tuned several postgres memory settings and added indexes.