Re: vmstat meaning

From: Juha Laiho (Juha.Laiho_at_iki.fi)
Date: 03/05/04 

Date: Fri, 05 Mar 2004 19:42:00 GMT

sankarmukh@yahoo.com (Sankar) said:
>One of our unix box running in solaris 2.6 always shows 0% idle.
>
>vmstat shows:
>sol1001> vmstat 3 3
> procs memory page disk faults
>cpu
> r b w swap free re mf pi po fr de sr s0 s1 s6 s3 in sy cs
>us sy id
> 0 0 13 824 632 0 0 0 0 0 0 0 4 1 0 3 4294967196 0 0
>-30 -8 -82
> 0 1 25 626960 16000 9 2 5720 90 776 0 150 1 0 0 48 1524 2391 2259
>20 16 65
> 0 0 25 626960 15744 9 0 5085 85 968 0 163 0 0 0 27 1309 2198 1987
>18 16 66
>sol1001>
>
>sar shows:
>
>inafpuxpdt01> sar -u 3 3
>
>SunOS sol1001 5.6 Generic_105181-29 sun4u 03/04/04
>
>14:35:51 %usr %sys %wio %idle
>14:35:54 4 18 78 0
>14:35:57 13 16 72 0
>14:36:00 6 15 79 0
>
>Average 8 16 76 0
>
>What does the first line in vmstat mean? why such a high number under
>faults? why negative numbers uber user,system and idle?

The first line is some kind of summary from system boot; the negative
numbers could be a result of some kind of counter overflow or perhaps
some overflow during the computation. More or less nothing to worry.

Where I would worry is that very high %wio you see with sar -- the
system is spending most of its wall-clock time waiting for I/O
completion of some kind. It could be either genuine filesystem I/O
or paging activity, but whatever it is it is bogging down your system.

iostat would be a good command to find out the details on this, though
you may need to play with the options a bit to find out which of
your filesystems and devices are the most loaded ones.

If it's paging activity that is causing that high %wio, then you'll
either need to get more physical memory to the machine or to reduce
the memory consumption somehow. "ps -fly" should be a good command
to find out about processes consuming large amounts of memory. 

-- 
Wolf  a.k.a.  Juha Laiho     Espoo, Finland
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"...cancel my subscription to the resurrection!" (Jim Morrison)

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