System Activity Report (SAR)
System Activity Report, in the first example, samples cumulative activity counters in the OS at n intervals of t seconds, whereas t should be 5 or greater. It saves the samples in the file in binary format if the -o option is specified. The default value of n is 1. Within the second instance, with no sampling interval specified, System Activity Report extracts data from a previously recorded file, either the one specified through An -f option or, by default, the standard system activity daily data file /var/adm/sa/sadd for the current day dd. The beginning and ending times of the report can be bound by the -s and -e time arguments of the form hh[:mm[:ss]]. A -i option selects records at second intervals. Or else, all the intervals found in the data file are reported.
In other case, subsets of data to be printed are specified through the given options:
-a It Reports use of file access system routines.
-b It Reports buffer activity.
-c It Reports system calls.
-d It Reports activity for every block device, which is, disk drives.
-g It Reports graphics activity.
-m It Reports message and semaphore activities.
-p It Reports paging activities.
-q It Reports average queue length although occupied and percent of time occupied.
-r It Reports unused memory pages and disk blocks.
-u It Reports CPU utilization (the default).
-v It Reports status of process, i-node, file tables and record lock tables.
-w It Reports system swapping and switching activity.
-y It Reports TTY device activity.
Practice
The given example is an demonstrate of the SAR command.
# SAR -a 22
17:56:20 iget/s namei/s dirbk/s (-a)
17:56:22 0 0 0
17:56:24 4 1 0
Average 2 1 0
Here two samples are occupied at an interval of two seconds.
iget/s denote the number of requests made for the inodes which were not in the directory name look up cache(dnlc). Here namei/s denotes the number of file system path searches per second. dirbk/s indicates this is the number of directory block reads issued per second.