04-11-2010
It's real hard to tell how frequently you're monitoring your statistics and unless you're looking at them very frequently, say every 10 seconds or so, you don't get a lot of help from your data. I do know the default sampling rate for sar is one sample every 10 minutes which might have made sense 20 years ago when computers were a lot slower but make no sense today. When sar tells you your cpu is loaded at 20%, how do you know it wasn't 100% for 2 minutes and 0 for 8? Same holds for everything else.
Personally I find looking at a single number and saying this is the CPU or network loads, isn't all that helpful either since nothing is constant. I find seeing numbers every second or so over a period of time when problems exist are much more helpful, but that's me...
-mark
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sar(1M) System Administration Commands sar(1M)
NAME
sar, sa1, sa2, sadc - system activity report package
SYNOPSIS
/usr/lib/sa/sadc [ t n] [ofile]
/usr/lib/sa/sa1 [ t n]
/usr/lib/sa/sa2 [-aAbcdgkmpqruvwy] [-e time] [-f filename] [-i sec] [-s time]
DESCRIPTION
System activity data can be accessed at the special request of a user (see sar(1)) and automatically, on a routine basis, as described
here. The operating system contains several counters that are incremented as various system actions occur. These include counters for CPU
utilization, buffer usage, disk and tape I/O activity, TTY device activity, switching and system-call activity, file-access, queue activ-
ity, inter-process communications, and paging. For more general system statistics, use iostat(1M), sar(1), or vmstat(1M).
sadc and two shell procedures, sa1 and sa2, are used to sample, save, and process this data.
sadc, the data collector, samples system data n times, with an interval of t seconds between samples, and writes in binary format to ofile
or to standard output. The sampling interval t should be greater than 5 seconds; otherwise, the activity of sadc itself may affect the sam-
ple. If t and n are omitted, a special record is written. This facility can be used at system boot time, when booting to a
multi-user state, to mark the time at which the counters restart from zero. For example, when accounting is enabled, the svc:/sys-
tem/sar:default service writes the restart mark to the daily data file using the command entry:
su sys -c "/usr/lib/sa/sadc /var/adm/sa/sa'date +%d'"
The shell script sa1, a variant of sadc, is used to collect and store data in the binary file /var/adm/sa/sadd, where dd is the current
day. The arguments t and n cause records to be written n times at an interval of t seconds, or once if omitted. The following entries in
/var/spool/cron/crontabs/sys will produce records every 20 minutes during working hours and hourly otherwise:
0 * * * 0-6 /usr/lib/sa/sa1
20,40 8-17 * * 1-5 /usr/lib/sa/sa1
See crontab(1) for details.
The shell script sa2, a variant of sar, writes a daily report in the file /var/adm/sa/sardd. See the OPTIONS section in sar(1) for an
explanation of the various options. The following entry in /var/spool/cron/crontabs/sys will report important activities hourly during the
working day:
5 18 * * 1-5 /usr/lib/sa/sa2 -s 8:00 -e 18:01 -i 1200 -A
FILES
/tmp/sa.adrfl address file
/var/adm/sa/sadd Daily data file
/var/adm/sa/sardd Daily report file
/var/spool/cron/crontabs/sys
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability |SUNWaccu |
+-----------------------------+-----------------------------+
SEE ALSO
crontab(1), sag(1), sar(1), svcs(1), timex(1), iostat(1M), svcadm(1M), vmstat(1M), attributes(5), smf(5)
System Administration Guide: Basic Administration
NOTES
The sar service is managed by the service management facility, smf(5), under the service identifier:
svc:/system/sar
Administrative actions on this service, such as enabling, disabling, or requesting restart, can be performed using svcadm(1M). The ser-
vice's status can be queried using the svcs(1) command.
SunOS 5.10 20 Aug 2004 sar(1M)