All IT students may expect shortly free lessons on Software Utilities The First batch of utilities are :-
10 Linux System Monitoring Tools Every SysAdmin Should Know
Need to monitor Linux server performance? Try these built-in command and a few add-on tools. Most Linux distributions are equipped with tons of monitoring. These tools provide metrics which can be used to get information about system activities. You can use these tools to find the possible causes of a performance problem. The commands discussed below are some of the most basic commands when it comes to system analysis and debugging server issues such as:
- Finding out bottlenecks.
- Disk (storage) bottlenecks.
- CPU and memory bottlenecks.
- Network bottlenecks.
#1: top – Process Activity Command
The top program provides a dynamic real-time view of a running system i.e. actual process activity. By default, it displays the most CPU-intensive tasks running on the server and updates the list every five seconds.
Fig.01: Linux top command
Commonly Used Hot Keys
The top command provides several useful hot keys:
|
Hot Key |
Usage |
| t | Displays summary information off and on. |
| m | Displays memory information off and on. |
| A | Sorts the display by top consumers of various system resources. Useful for quick identification of performance-hungry tasks on a system. |
| f | Enters an interactive configuration screen for top. Helpful for setting up top for a specific task. |
| o | Enables you to interactively select the ordering within top. |
| r | Issues renice command. |
| k | Issues kill command. |
| z | Turn on or off color/mono |
=> Related: How do I Find Out Linux CPU Utilization?
#2: vmstat – System Activity, Hardware and System Information
The command vmstat reports information about processes, memory, paging, block IO, traps, and cpu activity.
# vmstat 3
Sample Outputs:
procs ———–memory———- —swap– —–io—- –system– —–cpu——
r b swpd free buff cache si so bi bo in cs us sy id wa st
0 0 0 2540988 522188 5130400 0 0 2 32 4 2 4 1 96 0 0
1 0 0 2540988 522188 5130400 0 0 0 720 1199 665 1 0 99 0 0
0 0 0 2540956 522188 5130400 0 0 0 0 1151 1569 4 1 95 0 0
0 0 0 2540956 522188 5130500 0 0 0 6 1117 439 1 0 99 0 0
0 0 0 2540940 522188 5130512 0 0 0 536 1189 932 1 0 98 0 0
0 0 0 2538444 522188 5130588 0 0 0 0 1187 1417 4 1 96 0 0
0 0 0 2490060 522188 5130640 0 0 0 18 1253 1123 5 1 94 0 0
Display Memory Utilization Slabinfo
# vmstat -m
Get Information About Active / Inactive Memory Pages
# vmstat -a
=> Related: How do I find out Linux Resource utilization to detect system bottlenecks?
#3: w – Find Out Who Is Logged on And What They Are Doing
w command displays information about the users currently on the machine, and their processes.
# w username
# w vivek
Sample Outputs:
17:58:47 up 5 days, 20:28, 2 users, load average: 0.36, 0.26, 0.24
USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT
root pts/0 10.1.3.145 14:55 5.00s 0.04s 0.02s vim /etc/resolv.conf
root pts/1 10.1.3.145 17:43 0.00s 0.03s 0.00s w
#4: uptime – Tell How Long The System Has Been Running
The uptime command can be used to see how long the server has been running. The current time, how long the system has been running, how many users are currently logged on, and the system load averages for the past 1, 5, and 15 minutes.
# uptime
Output:
18:02:41 up 41 days, 23:42, 1 user, load average: 0.00, 0.00, 0.00
1 can be considered as optimal load value. The load can change from system to system. For a single CPU system 1 – 3 and SMP systems 6-10 load value might be acceptable.
#5: ps – Displays The Processes
ps command will report a snapshot of the current processes. To select all processes use the -A or -e option:
# ps -A
Sample Outputs:
PID TTY TIME CMD
1 ? 00:00:02 init
2 ? 00:00:02 migration/0
3 ? 00:00:01 ksoftirqd/0
4 ? 00:00:00 watchdog/0
5 ? 00:00:00 migration/1
6 ? 00:00:15 ksoftirqd/1
….
…..
4881 ? 00:53:28 java
4885 tty1 00:00:00 mingetty
4886 tty2 00:00:00 mingetty
4887 tty3 00:00:00 mingetty
4888 tty4 00:00:00 mingetty
4891 tty5 00:00:00 mingetty
4892 tty6 00:00:00 mingetty
4893 ttyS1 00:00:00 agetty
12853 ? 00:00:00 cifsoplockd
12854 ? 00:00:00 cifsdnotifyd
14231 ? 00:10:34 lighttpd
14232 ? 00:00:00 php-cgi
54981 pts/0 00:00:00 vim
55465 ? 00:00:00 php-cgi
55546 ? 00:00:00 bind9-snmp-stat
55704 pts/1 00:00:00 ps
ps is just like top but provides more information.
Show Long Format Output
# ps -Al
To turn on extra full mode (it will show command line arguments passed to process):
# ps -AlF
To See Threads ( LWP and NLWP)
# ps -AlFH
To See Threads After Processes
# ps -AlLm
Print All Process On The Server
# ps ax
# ps axu
Print A Process Tree
# ps -ejH
# ps axjf
# pstree
Print Security Information
# ps -eo euser,ruser,suser,fuser,f,comm,label
# ps axZ
# ps -eM
See Every Process Running As User Vivek
# ps -U vivek -u vivek u
Set Output In a User-Defined Format
# ps -eo pid,tid,class,rtprio,ni,pri,psr,pcpu,stat,wchan:14,comm
# ps axo stat,euid,ruid,tty,tpgid,sess,pgrp,ppid,pid,pcpu,comm
# ps -eopid,tt,user,fname,tmout,f,wchan
Display Only The Process IDs of Lighttpd
# ps -C lighttpd -o pid=
OR
# pgrep lighttpd
OR
# pgrep -u vivek php-cgi
Display The Name of PID 55977
# ps -p 55977 -o comm=
Find Out The Top 10 Memory Consuming Process
# ps -auxf | sort -nr -k 4 | head -10
Find Out top 10 CPU Consuming Process
# ps -auxf | sort -nr -k 3 | head -10
#6: free – Memory Usage
The command free displays the total amount of free and used physical and swap memory in the system, as well as the buffers used by the kernel.
# free
Sample Output:
total used free shared buffers cached
Mem: 12302896 9739664 2563232 0 523124 5154740
-/+ buffers/cache: 4061800 8241096
Swap: 1052248 0 1052248
=> Related: :
- Linux Find Out Virtual Memory PAGESIZE
- Linux Limit CPU Usage Per Process
- How much RAM does my Ubuntu / Fedora Linux desktop PC have?
#7: iostat – Average CPU Load, Disk Activity
The command iostat report Central Processing Unit (CPU) statistics and input/output statistics for devices, partitions and network filesystems (NFS).
# iostat
Sample Outputs:
Linux 2.6.18-128.1.14.el5 (www03.nixcraft.in) 06/26/2009
avg-cpu: %user %nice %system %iowait %steal %idle
3.50 0.09 0.51 0.03 0.00 95.86
Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
sda 22.04 31.88 512.03 16193351 260102868
sda1 0.00 0.00 0.00 2166 180
sda2 22.04 31.87 512.03 16189010 260102688
sda3 0.00 0.00 0.00 1615 0
=> Related: : Linux Track NFS Directory / Disk I/O Stats
#8: sar – Collect and Report System Activity
The sar command is used to collect, report, and save system activity information. To see network counter, enter:
# sar -n DEV | more
To display the network counters from the 24th:
# sar -n DEV -f /var/log/sa/sa24 | more
You can also display real time usage using sar:
# sar 4 5
Sample Outputs:
Linux 2.6.18-128.1.14.el5 (www03.nixcraft.in) 06/26/2009
06:45:12 PM CPU %user %nice %system %iowait %steal %idle
06:45:16 PM all 2.00 0.00 0.22 0.00 0.00 97.78
06:45:20 PM all 2.07 0.00 0.38 0.03 0.00 97.52
06:45:24 PM all 0.94 0.00 0.28 0.00 0.00 98.78
06:45:28 PM all 1.56 0.00 0.22 0.00 0.00 98.22
06:45:32 PM all 3.53 0.00 0.25 0.03 0.00 96.19
Average: all 2.02 0.00 0.27 0.01 0.00 97.70
=> Related: : How to collect Linux system utilization data into a file
#9: mpstat – Multiprocessor Usage
The mpstat command displays activities for each available processor, processor 0 being the first one. mpstat -P ALL to display average CPU utilization per processor:
# mpstat -P ALL
Sample Output:
Linux 2.6.18-128.1.14.el5 (www03.nixcraft.in) 06/26/2009
06:48:11 PM CPU %user %nice %sys %iowait %irq %soft %steal %idle intr/s
06:48:11 PM all 3.50 0.09 0.34 0.03 0.01 0.17 0.00 95.86 1218.04
06:48:11 PM 0 3.44 0.08 0.31 0.02 0.00 0.12 0.00 96.04 1000.31
06:48:11 PM 1 3.10 0.08 0.32 0.09 0.02 0.11 0.00 96.28 34.93
06:48:11 PM 2 4.16 0.11 0.36 0.02 0.00 0.11 0.00 95.25 0.00
06:48:11 PM 3 3.77 0.11 0.38 0.03 0.01 0.24 0.00 95.46 44.80
06:48:11 PM 4 2.96 0.07 0.29 0.04 0.02 0.10 0.00 96.52 25.91
06:48:11 PM 5 3.26 0.08 0.28 0.03 0.01 0.10 0.00 96.23 14.98
06:48:11 PM 6 4.00 0.10 0.34 0.01 0.00 0.13 0.00 95.42 3.75
06:48:11 PM 7 3.30 0.11 0.39 0.03 0.01 0.46 0.00 95.69 76.89
=> Related: : Linux display each multiple SMP CPU processors utilization individually.
10) dbspace – Keep Tracking HD Storage space
kpvarkeys 