MONITORING UNIX SYSTEM PERFORMANCE

crontab: This command tells the system to schedule a job at a particular time and date and

execute the job accordingly. There are many command line options in crontab. In the below example “crontab –l” shows the list of scheduled jobs and copies the results to an output file.

In the same way, we can schedule a new job by using “crontab –e”

For example, If we want to run a job on every day, every hour

0 * * * * sh/pathofthe_job/jobname.sh

uptime: It tells about the load averages on the system. In the below example the uptime displays the time the system has been up, and the three load averages for the system. The load averages are the average number of process ready to run during the last 1, 5 and 15 minutes.

Process Status (ps): It tells about the processes running in the systems. There are many command line options in ps which are shown in the below snapshot.

For example the command “ps –e” shows all the processes running in the system.Suppose if we want to get the status of only mysql process we have to give the following command “ps –ef|grep mysql”.

iostat: The iostat will display the current CPU load average and disk I/O information.

Syntax: iostat interval count

The below snapshot shows average cpu load and disk i/o. In this “iostat 1 5” states to update the information of disk i/o and cpu load average for every one second totally for five times.

sar: It is used to get the information about CPU utilization, system calls, memory allocation, buffer activity, paging activity, and many more. There are many command line options in sar which can be used in combinations. For example the below snapshot shows two commands “sar –u 2 5” and “sar –pd 2 5”. The first one “sar –u 2 5” gives the information on cpu utilization for every two seconds totally five times. The second one “sar –pd 2 5” gives the disk i/o for every two seconds totally five times.

Virtual memory statistics (vmstat): vmstat reports information about processes, memory, paging, block IO, traps, and cpu activity. The below snapshot of vmstat shows the memory every 1 second and for 5 times vmstat 1 5

Netstat: It is used for networking reports. There are many command line options in netstat which can used in combinations. For example, to diagnose a networking problem “netstat –i” could be used in the following way:

Name Mtu Network Address Ipkts Opkts Odrop

eg1 1500 204.89.162 dxi4.dxi.com 2275517 3783974 0eg0 1500 38.254.211 dxifour.dxi.com 4716968 2862227 0loop 1536 loopback-net localhost 0 0 0

Here Odrop are the number of packets that were dropped or discarded without reaching destination. The below snapshot shows all the command line options that are available in “netstat”.

top: Top produces a list of all the currently running processes listed in order of CPU usage. The list is continuously updated at five second intervals by default, and there are options to shorten or lengthen the update period. There are many command line options in top. In top by default only some of the fields are displayed. We can add the required additional fields using ‘shift+o’ which gives total field descriptions. We can also sort process ids using ‘shift+<’. The below snapshot shows how the top command works.