Interpreting 'sar' output

Interpreting 'sar' output

Post by Brian Mathi » Wed, 29 Apr 1998 04:00:00



Hello,

I've been keeping track of machine statistics using 'sar' for the past
month.  I've mostly been paying attention to the runqueue sizes, and our
machine seems overloaded (runqueues of 6 on average, spikes up to 13;  I
understand a good target is around 2, with 4 being considered high).  In
any case, the statistics have remained consistant, up until last
friday.  An average day would look something like this:
---------------------
intserv1: sar -q

SunOS idev 5.5.1 Generic_103640-08 sun4u    04/09/98

12:06:00 runq-sz %runocc swpq-sz %swpocc
12:07:00     4.4     100                
12:08:00     5.5     100                
12:09:00     4.3     100                
12:10:00     3.2     100                
12:11:00     7.8      99                
12:12:00     5.7     101                
12:13:00     4.2     100                
12:14:00     6.9     100
---------------------

On friday, and since, however, it has been looking like this:

--------------------
intserv1: sar -q

SunOS idev 5.5.1 Generic_103640-08 sun4u    04/24/98

10:11:00 runq-sz %runocc swpq-sz %swpocc
10:12:00    16.7      10
10:13:00     2.0       7
10:14:00    18.4      15
10:15:00    11.9      15
10:16:00     3.8      20
10:17:00    13.6       8
10:18:00     6.0      10
10:19:00    17.4      13
---------------------

The runqueue size seems very erratic, and %runocc is much lower
(normally at %100).  Swap, memory, and everything else seem pretty much
ok though, as far as I can tell.

Can anyone shed some light on what might cause this?  There have not
been any significant changes made to the machine.  I get the feeling
that something is broken, either 'sar' or something else on the machine.

Also, I am running 'sar' every minute from cron, and at the same time
this started happening, I get blank entries in the log.  There is a time
stamp, just no data.

Any help would be appreciated.

Brian Mathis

PS> I'm also looking for a good place to find information of
interpreting 'sar' data.

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