sar Commands Examples

- sar is a very useful command provided in the Linux/UNIX OS. It comes from sysstat package.

- Using sar command we can get many important stats from the server like CPU usage, memory usage, swap, IO, disk IO, network, paging etc.

- Not only we can get the current statistics but also stats for previous date from the sar log files (/var/log/sa/), remember by default sar stores only latest 7 days data into "/var/log/sa/sa1-31" files. (1-31 for months dates)

- We can make sar to keep logs for more days by editing "/etc/sysconfig/sysstat" file and specifying "HISTORY" attribute.

- I have covered almost all the sar command options here.

1. Installing sar command

- To install sar command, you need to have "sysstat" package.                 # yum install sysstat                 # rpm -ivh sysstat-2.3.4 - To configure the sar to retain logs of more than default 7 days.                 # vi /etc/sysconfig/sysstat                 Change the "HISTORY" parameter

2. CPU usage

- To get current CPU usage                 # sar 2 10                 # sar -p 2 10                 # sar  -P ALL 2 10 - To get the CPU usage for previous date, consider 14th                 # sar -P ALL -f /var/log/sa/sa14 - To get the CPU usage for 10th of month, from 7 AM to 3 PM (i.e. with specifying the time)                 # sar -P ALL -f /var/log/sa/sa10 -s 07:00:00 -e 15:00:00                                            %user - CPU time used for user processes                                          %nice - CPU time used for low priority processes                                          %system - CPU time used for kernel space                                          %iowait - CPU time spent in disk IO wait                                          %steal - Percentage of time virtual CPU waits for real CPU                                          %idle - CPU time in idle state

3. Memory usage

- To get current memory usage                 # sar -r 2 10 - To get memory usage for previous date, consider 14th                 # sar -r -f /var/log/sa/sa14 - To get memory usage for the 10th of month, from 7 AM to 3 PM (i.e. with specifying the time)                 # sar -r -f /var/log/sa/sa10 -s 07:00:00 -e 15:00:00                                           kbmemfree - Memory free in KB                                          kbmemused - Memory used in KB                                          %memused - Percentage of memory used                                          kbbuffers - Size of buffer in KB                                          kbcached - Size of Cache in KB                                          kbcommit - Size of memory in commit state                                          %commit - Percentage of memory in commite state

4. Swap usage

- To get current swap usage                 # sar -S 2 10 - To get swap usage for previous date, consider 14th                 # sar -S -f /var/log/sa/sa14 - To get swap usage for the 10th of month, from 7 AM to 3 PM                 # sar -S -f /var/log/sa/sa10 -s 07:00:00 -e 15:00:00                                           kbswpfree - Swap free in KB                                          kbswpused - Swap used in KB                                          %swpused - Percentage of swap used                                          kbswpcad - Amount  of  cached  swap memory in kilobytes                                          %swpcad - Percentage of cached swap memory

5. Load Average

- To get current load average stats                 # sar -q 2 10 - To get load average stats for previous date, consider 14th                 # sar -q -f /var/log/sa/sa14 - To get load average stats for the 10th of month, from 7 AM to 3 PM                 # sar -q -f /var/log/sa/sa10 -s 07:00:00 -e 15:00:00                                           runq-sz - number of tasks waiting for run time                                          plist-sz - Number of tasks in the task list                                          ldavg-1 - load  average  for  the last minute                                          ldavg-5 - load  average  for  the last 5 minute                                          ldavg-15 - load  average  for  the last 15 minute

6. Paging usage

- To get current paging usage                 # sar -B 2 10 - To get paging usage for previous date, consider 14th                 # sar -B -f /var/log/sa/sa14 - To get paging usage for the 10th of month, from 7 AM to 3 PM                 # sar -B -f /var/log/sa/sa10 -s 07:00:00 -e 15:00:00                                           pgpgin/s - Total number of kilobytes the system paged in from disk per second                                          pgpgout/s - Total  number of kilobytes the system paged out to disk per second                                          fault/s - Number of page faults                                          majflt/s - Number  of major faults the system has made per second                                          pgfree/s - Number of pages placed on the free list by the system per second                                          pgscank/s - Number of pages scanned by the kswapd daemon per second                                          pgscand/s - Number of pages scanned directly per second                                          pgsteal/s - Number of pages the system has reclaimed from cache                                          %vmeff - Efficiency of page reclaim

7. IO usage

- To get current IO usage                 # sar -b 2 10 - To get IO usage for previous date, consider 14th                 # sar -b -f /var/log/sa/sa14 - To get IO usage for the 10th of month, from 7 AM to 3 PM                 # sar -b -f /var/log/sa/sa10 -s 07:00:00 -e 15:00:00                                           tps - Total  number  of transfers per second                                          rtps - Total number of read requests per second                                          wtps - Total number of write requests per second                                          bread/s - Total  amount of data read from the devices in blocks per second                                          bwrtn/s - Total amount of data written to devices in blocks per second

8. Disk IO usage

- To get current disk IO usage                 # sar -d -p 2 10 - To get disk IO usage for previous date, consider 14th                 # sar -d -p -f /var/log/sa/sa14 - To get disk IO usage for the 10th of month, from 7 AM to 3 PM                 # sar -d -p -f /var/log/sa/sa10 -s 07:00:00 -e 15:00:00                                           tps - number of transfers per second                                          rd_sec/s - Number of sectors read from the device                                          wr_sec/s - Number of sectors written to the device                                          avgrq-sz - The average size (in sectors) of the requests that were issued to the device                                          avgqu-sz - The average queue length of the requests that were issued to the device                                          await - The average time (in milliseconds) for I/O requests issued to the device to be served                                          svctm - The average service time (in milliseconds) for I/O requests                                          %util - Percentage  of CPU time during which I/O requests

9. Networking stats 

- To get current network device stats                 # sar -n DEV 2 10 - To get network device stats for previous date, consider 14th                 # sar -n DEV -f /var/log/sa/sa14 - To get network device stats for the 10th of month, from 7 AM to 3 PM                 # sar -n DEV -f /var/log/sa/sa10 -s 07:00:00 -e 15:00:00                                          rxpck/s - Total number of packets received per second                                          txpck/s - Total number of packets transmitted per second                                          rxkB/s - Total number of kilobytes received per second                                          txkB/s - Total number of kilobytes transmitted per second                                          rxcmp/s - Number of compressed packets received per second                                          txcmp/s - Number of compressed packets transmitted per second                                          rxmcst/s - Number of multicast packets received per second

10. NFS stats 

- To get current network device stats                 # sar -n NFS 2 10 - To get network device stats for previous date, consider 14th                 # sar -n NFS -f /var/log/sa/sa14 - To get network device stats for the 10th of month, from 7 AM to 3 PM                 # sar -n NFS -f /var/log/sa/sa10 -s 07:00:00 -e 15:00:00                                          call/s - Number of RPC requests made per second                                          retrans/s - Number of RPC requests per second, those which needed  to  be  retransmitted                                          read/s - Number of âreadâ RPC calls made per second                                          write/s - Number of âwriteâ RPC calls made per second                                          access/s - Number of âaccessâ RPC calls made per second                                          getatt/s - Number of âgetattrâ RPC calls made per second

11. Power Management Stats 

- To get current power management usage                 # sar -m 2 10 - To get power management usage for previous date, consider 14th                 # sar -m -f /var/log/sa/sa14 - To get power management usage for the 10th of month, from 7 AM to 3 PM                 # sar -m ALL -f /var/log/sa/sa10 -s 07:00:00 -e 15:00:00

12. Memory Stats (Page activities) 

- To get current memory stats                 # sar -R 2 10 - To get memory stats for previous date, consider 14th                 # sar -R -f /var/log/sa/sa14 - To get memory stats for the 10th of month, from 7 AM to 3 PM                 # sar -R ALL -f /var/log/sa/sa10 -s 07:00:00 -e 15:00:00                                          frmpg/s - Number  of memory pages freed by the system per second                                          bufpg/s - Number  of  additional  memory  pages used as buffers by the system per second                                          campg/s - Number of additional memory pages cached by the system per second

Other Sysstat Utilities

- sar          : It collects and displays ALL system activities statistics. - sadc        : It stands for “system activity data collector”. This is the sar backend tool that does the data collection.  - sa1          : It stores system activities in binaryhttps://images-blogger-this purpose. sa1 runs from cron. - sa2          : It creates daily summary of the collected statistics. sa2 runs from cron. - sadf         : It can generate sar report in CSV, XML, and various other formats. Use this to integrate sar data with other tools. - iostat       : It generates CPU, I/O statistics - mpstat     : It displays CPU statistics. - pidstat     : It reports statistics based on the process id (PID) - nfsiostat   : It displays NFS I/O statistics. - cifsiostat  : It generates CIFS statistics.

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