SAR command is  collect and report system activity in the operating system,  easily to  get system status  number of times spaced at the specified intervals in seconds.
Analysis of load values of different sub-system process like, CPU, Network interface, Memory Usage, Load and etc.

How to Install :

You want get these logs, install sysstat package in your system using yum command or apt-get.

 Fedora / CentOS /Redhat
 

# yum install sysstat

Debain / Ubuntu
 
# sudo apt-get install sysstat

Configuration :
 
#  cat /etc/sysconfig/sysstat


# How long to keep log files (in days).

# If value is greater than 28, then log files are kept in

# multiple directories, one for each month.

HISTORY=28



# Compress (using gzip or bzip2) sa and sar files older than (in days):

COMPRESSAFTER=31


By default set cron job for collect logs,
 
# cat /etc/cron.d/sysstat


# Run system activity accounting tool every 10 minutes

*/10 * * * * root /usr/lib64/sa/sa1 1 1



# Generate a daily summary of process accounting at 23:53

53 23 * * * root /usr/lib64/sa/sa2 -A


Command Reports:

Sysstat logs stores in /var/log/sa/ direcotry,

Displaying the CPU Load

The following command shows report CPU load average on 11 th of the current month,
 
# sar -P ALL -f /var/log/sa/sa11


08:40:01  IST     CPU     %user     %nice   %system   %iowait    %steal     %idle

08:50:01  IST     all      0.03      0.00      0.06      0.58      0.01     99.32

08:50:01  IST       0      0.03      0.00      0.06      0.58      0.01     99.32



Average:        CPU     %user     %nice   %system   %iowait    %steal     %idle

Average:        all      0.04      0.00      0.05      0.99      0.02     98.90

Average:          0      0.04      0.00      0.05      0.99      0.02     98.90

Displaying the RAM memory load 

The following command shows RAM memory usage reports on current day,
 
# sar -r


Linux 2.6.32-71.29.1.el6.x86_64 (host.thelinuxfaq.com)     Thursday 22 January 2015     _x86_64_    (1 CPU)



04:30:02  IST kbmemfree kbmemused  %memused kbbuffers  kbcached  kbcommit   %commit

05:31:05  IST     13684   1984888     99.32      2128     25460   6411100    105.19

05:42:13  IST     16808   1981764     99.16      2032     28568   7642764    125.40

06:24:03  IST     13716   1984856     99.31      2136     29068   8273452    135.75

06:50:54  IST   1076812    921760     46.12     12632    475708    890436     14.61

Average:       295721   1702851     85.20    117332   1088327    900681     14.78


Displaying Load average:

The following command shows report load average on current day,
 
# sar -q


04:30:02  IST   runq-sz  plist-sz   ldavg-1   ldavg-5  ldavg-15

05:20:01  IST         3       131      0.70      0.81      0.80

05:31:05  IST         0       637    184.33    142.72     71.64

05:42:13  IST         0       867    360.59    275.42    170.43

06:24:03  IST         0       819    274.38    299.45    315.26

06:50:54  IST         4       166      6.52      2.43      0.87

Average:            3       144      7.70      6.82      5.43

Give interval time of 1 second and shows 3 reports,
 
# sar -q 1 3


Linux 3.13.0-37-generic (laks)     Friday 30 January 2015     _x86_64_    (4 CPU)



11:33:25  IST   runq-sz  plist-sz   ldavg-1   ldavg-5  ldavg-15   blocked

11:33:26  IST         0       473      0.15      0.28      0.29         0

11:33:27  IST         0       473      0.15      0.28      0.29         0

11:33:28  IST         1       473      0.14      0.27      0.29         0

Average:            0       473      0.15      0.28      0.29         0


Displaying Network Statistics :

The following command shows network values on current day, DEV -> eth0
 
# sar -n DEV


06:50:54  IST     IFACE   rxpck/s   txpck/s    rxkB/s    txkB/s   rxcmp/s   txcmp/s  rxmcst/s

07:00:01  IST        lo      3.79      3.79      0.48      0.48      0.00      0.00      0.00

07:00:01  IST      eth0     55.12     29.81      5.47     57.30      0.00      0.00      0.00

07:10:01  IST        lo      2.88      2.88      0.38      0.38      0.00      0.00      0.00

Average:           lo      0.00      0.00      0.00      0.00      0.00      0.00      0.00

Average:         eth0      0.00      0.00      0.00      0.00      0.00      0.00      0.00


Give interval time of 1 second and shows 2 reports,
 
# sar -n  DEV 1 2


Linux 2.6.32-71.29.1.el6.x86_64 (host.thelinuxfaq.com)     Friday 30 January 2015     _x86_64_    (1 CPU)



11:32:05  IST     IFACE   rxpck/s   txpck/s    rxkB/s    txkB/s   rxcmp/s   txcmp/s  rxmcst/s

11:32:06  IST        lo      3.19      3.19      0.25      0.25      0.00      0.00      0.00

11:32:06  IST      eth0     12.77      2.66      1.69      0.96      0.00      0.00      0.00



11:32:06  IST     IFACE   rxpck/s   txpck/s    rxkB/s    txkB/s   rxcmp/s   txcmp/s  rxmcst/s

11:32:07  IST        lo      4.04      4.04      0.39      0.39      0.00      0.00      0.00

11:32:07  IST      eth0      5.56      2.02      1.07      0.34      0.00      0.00      0.00



Average:        IFACE   rxpck/s   txpck/s    rxkB/s    txkB/s   rxcmp/s   txcmp/s  rxmcst/s

Average:           lo      3.63      3.63      0.32      0.32      0.00      0.00      0.00

Average:         eth0      9.07      2.33      1.38      0.64      0.00      0.00      0.00

CPU Usage of Individual CPU or Core (sar -P)

Displaying I/O Transfer:
 
#  sar -b


Linux 2.6.32-71.29.1.el6.x86_64 (host.thelinuxfaq.com)     Thursday 22 January 2015     _x86_64_    (1 CPU)



04:30:02  IST       tps      rtps      wtps   bread/s   bwrtn/s

05:20:01  IST     11.31      0.03     11.28      0.41    102.17

05:31:05  IST    121.52     57.23     64.30   2473.33   4040.15

05:42:13  IST    106.05     75.11     30.95   2774.17   1943.50

06:24:03  IST     95.98     60.98     35.00   2299.69    853.22

06:50:54  IST    100.00    100.00    100.00    100.00    100.00

07:00:01  IST      7.58      1.94      5.64    104.72     53.06

Average:       100.00    100.00    100.00    100.00    100.00


tps : This is specified to total number transfer per second, its an I/O request to a physical device. Multiple logcal request combined combined into a single I/O  to the device.

rtps: This is specified to total number of read request per second shared to physical devices.

wtps: This si specified to Total number of write requests per second shared to physical devices.

bread/s : This is specified to total number of data read from the devices in block per second.

bwrtn/s : This is specified to total number of data written to device in block per second.
  
Displaying CPU utilization for each 2 seconds. 3 lines.
 
# sar -u 2 3


Linux 2.6.32-71.29.1.el6.x86_64 (host.thelinuxfaq.com)     Friday 30 January 2015     _x86_64_    (1 CPU)



11:15:39  IST     CPU     %user     %nice   %system   %iowait    %steal     %idle

11:15:41  IST     all      1.28      0.00      1.53      2.56      0.00     94.63

11:15:43  IST     all      4.61      0.00      2.71      0.00      0.00     92.68

11:15:45  IST     all      0.00      0.00      0.25      4.03      0.00     95.72

Average:        all      1.90      0.00      1.47      2.25      0.00     94.38

Displaying memory and network statistics:

The following command shows report of  memory and networks on 29th  
 
#  sar -r -n DEV -f /var/log/sa/sa29


10:40:01  IST     IFACE   rxpck/s   txpck/s    rxkB/s    txkB/s   rxcmp/s   txcmp/s  rxmcst/s

10:50:02  IST        lo      0.10      0.10      0.02      0.02      0.00      0.00      0.00

10:50:02  IST      eth0     13.70      0.09      0.65      0.02      0.00      0.00      0.00

11:00:01  IST        lo      0.10      0.10      0.02      0.02      0.00      0.00      0.00

11:00:01  IST      eth0     13.62      0.09      0.65      0.02      0.00      0.00      0.00

Average:           lo      7.93      7.93      2.39      2.39      0.00      0.00      0.00

Average:         eth0     15.84      1.94      1.09      1.05      0.00      0.00      0.00


Also can viewing report on current day, 

Display context switch :
 
The following command shows report the total number of processes created per second, and total number of context switches,
 
# sar -w 1 3


Linux 3.13.0-37-generic (laks)     Friday 30 January 2015     _x86_64_    (4 CPU)



11:32:08  IST    proc/s   cswch/s

11:32:09  IST      0.00   1211.00

11:32:10  IST      0.00   1217.00

11:32:11  IST      0.00   1218.00

Average:         0.00   1215.33


Displaying yesterday logs report:

The following command can help to views on yesterday report.
 
# sar -f /var/log/sa/sa$(date +%d -d yesterday)


Linux 2.6.18-164.2.1.el5xen (host.thelinuxfaq.com)     02/10/15



00:00:01          CPU     %user     %nice   %system   %iowait    %steal     %idle

00:10:01          all     25.42      0.00     41.81     13.92      3.59     15.27

00:20:01          all     28.26      0.00     52.86      4.16      4.93      9.79

00:30:01          all     26.89      0.00     41.00      6.33      3.56     22.22

00:40:01          all     27.00      0.00     34.05      6.11      2.85     30.00


If you want to save the statistics:
 
# sar -A > $(date +`hostname`-%d-%m-%y-%H%M.log)

To Print the Values at particular time.
 
# sar -f /var/log/sa/sa10 -s 23:00:00

Find Sar Version:
 
# sar -V


sysstat version 10.2.0

(C) Sebastien Godard (sysstat <at> orange.fr)