Install Sysstat in Linux
# yum -y install sysstat
- vmstat – Summary information of Memory, Processes, Paging etc.
- iostat – Central Processing Unit (CPU) statistics and input/output statistics for devices and partitions.
6 Vmstat Command Examples in Linux
1. List Active and Inactive Memory
In the below example, there are six columns. The significant of the columns are explained in man page ofvmstat in details. Most important fields are free under memory and si, so under swap column.
[root@tecmint ~]# vmstat -a procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu----- r b swpd free inact active si so bi bo in cs us sy id wa st 1 0 0 810420 97380 70628 0 0 115 4 89 79 1 6 90 3 0
- Free – Amount of free/idle memory spaces.
- si – Swaped in every second from disk in Kilo Bytes.
- so – Swaped out every second to disk in Kilo Bytes.
Note: If you run vmstat without parameters it’ll displays summary report since system boot.
2. Execute vmstat ‘X’ seconds and (‘N’number of times)
With this command, vmstat execute every two seconds and stop automatically after executing six intervals.
[root@tecmint ~]# vmstat 2 6 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 810420 22064 101368 0 0 56 3 50 57 0 3 95 2 0 0 0 0 810412 22064 101368 0 0 0 0 16 35 0 0 100 0 0 0 0 0 810412 22064 101368 0 0 0 0 14 35 0 0 100 0 0 0 0 0 810412 22064 101368 0 0 0 0 17 38 0 0 100 0 0 0 0 0 810412 22064 101368 0 0 0 0 17 35 0 0 100 0 0 0 0 0 810412 22064 101368 0 0 0 0 18 36 0 1 100 0 0
3. Vmstat with timestamps
vmstat command with -t parameter shows timestamps with every line printed as shown below.
[tecmint@tecmint ~]$ vmstat -t 1 5 procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------ ---timestamp--- r b swpd free buff cache si so bi bo in cs us sy id wa st 0 0 0 632028 24992 192244 0 0 70 5 55 78 1 3 95 1 0 2012-09-02 14:57:18 IST 1 0 0 632028 24992 192244 0 0 0 0 171 514 1 5 94 0 0 2012-09-02 14:57:19 IST 1 0 0 631904 24992 192244 0 0 0 0 195 600 0 5 95 0 0 2012-09-02 14:57:20 IST 0 0 0 631780 24992 192244 0 0 0 0 156 524 0 5 95 0 0 2012-09-02 14:57:21 IST 1 0 0 631656 24992 192244 0 0 0 0 189 592 0 5 95 0 0 2012-09-02 14:57:22 IST
4. Statistics of Various Counter
vmstat command and -s switch displays summary of various event counters and memory statistics.
[tecmint@tecmint ~]$ vmstat -s 1030800 total memory 524656 used memory 277784 active memory 185920 inactive memory 506144 free memory 26864 buffer memory 310104 swap cache 2064376 total swap 0 used swap 2064376 free swap 4539 non-nice user cpu ticks 0 nice user cpu ticks 11569 system cpu ticks 329608 idle cpu ticks 5012 IO-wait cpu ticks 79 IRQ cpu ticks 74 softirq cpu ticks 0 stolen cpu ticks 336038 pages paged in 67945 pages paged out 0 pages swapped in 0 pages swapped out 258526 interrupts 392439 CPU context switches 1346574857 boot time 2309 forks
5. Disks Statistics
vmstat with -d option display all disks statistics.
[tecmint@tecmint ~]$ vmstat -d disk- ------------reads------------ ------------writes----------- -----IO------ total merged sectors ms total merged sectors ms cur sec ram0 0 0 0 0 0 0 0 0 0 0 ram1 0 0 0 0 0 0 0 0 0 0 ram2 0 0 0 0 0 0 0 0 0 0 ram3 0 0 0 0 0 0 0 0 0 0 ram4 0 0 0 0 0 0 0 0 0 0 ram5 0 0 0 0 0 0 0 0 0 0 ram6 0 0 0 0 0 0 0 0 0 0 ram7 0 0 0 0 0 0 0 0 0 0 ram8 0 0 0 0 0 0 0 0 0 0 ram9 0 0 0 0 0 0 0 0 0 0 ram10 0 0 0 0 0 0 0 0 0 0 ram11 0 0 0 0 0 0 0 0 0 0 ram12 0 0 0 0 0 0 0 0 0 0 ram13 0 0 0 0 0 0 0 0 0 0 ram14 0 0 0 0 0 0 0 0 0 0 ram15 0 0 0 0 0 0 0 0 0 0 loop0 0 0 0 0 0 0 0 0 0 0 loop1 0 0 0 0 0 0 0 0 0 0 loop2 0 0 0 0 0 0 0 0 0 0 loop3 0 0 0 0 0 0 0 0 0 0 loop4 0 0 0 0 0 0 0 0 0 0 loop5 0 0 0 0 0 0 0 0 0 0 loop6 0 0 0 0 0 0 0 0 0 0 loop7 0 0 0 0 0 0 0 0 0 0 sr0 0 0 0 0 0 0 0 0 0 0 sda 7712 5145 668732 409619 3282 28884 257402 644566 0 126 dm-0 11578 0 659242 1113017 32163 0 257384 8460026 0 126 dm-1 324 0 2592 3845 0 0 0 0 0 2
6. Display Statistics in Megabytes
The vmstat displays in Megabytes with parameters -S and M(Uppercase & megabytes). By default vmstatdisplays statistics in kilobytes.
[root@tecmint ~]# vmstat -S M 1 5 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 0 346 53 476 0 0 95 8 42 55 0 2 96 2 0 0 0 0 346 53 476 0 0 0 0 12 15 0 0 100 0 0 0 0 0 346 53 476 0 0 0 0 32 62 0 0 100 0 0 0 0 0 346 53 476 0 0 0 0 15 13 0 0 100 0 0 0 0 0 346 53 476 0 0 0 0 34 61 0 1 99 0 0
6 Iostat Command Examples in Linux
7. Display CPU and I/O statistics
iostat without arguments displays CPU and I/O statistics of all partitions as shown below.
[root@tecmint ~]# iostat Linux 2.6.32-279.el6.i686 (tecmint.com) 09/03/2012 _i686_ (1 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 0.12 0.01 1.54 2.08 0.00 96.24 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sda 3.59 161.02 13.48 1086002 90882 dm-0 5.76 159.71 13.47 1077154 90864 dm-1 0.05 0.38 0.00 2576 0
8. Shows only CPU Statistics
iostat with -c arguments displays only CPU statistics as shown below.
[root@tecmint ~]# iostat -c Linux 2.6.32-279.el6.i686 (tecmint.com) 09/03/2012 _i686_ (1 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 0.12 0.01 1.47 1.98 0.00 96.42
9. Shows only Disks I/O Statistics
iostat with -d arguments displays only disks I/O statistics of all partitions as shown.
[root@tecmint ~]# iostat -d Linux 2.6.32-279.el6.i686 (tecmint.com) 09/03/2012 _i686_ (1 CPU) Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sda 3.35 149.81 12.66 1086002 91746 dm-0 5.37 148.59 12.65 1077154 91728 dm-1 0.04 0.36 0.00 2576 0
10. Shows I/O statistics only of a single device.
By default it displays statistics of all partitions, with -p and device name arguments displays only disks I/Ostatistics for specific device only as shown.
[root@tecmint ~]# iostat -p sda Linux 2.6.32-279.el6.i686 (tecmint.com) 09/03/2012 _i686_ (1 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 0.11 0.01 1.44 1.92 0.00 96.52 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sda 3.32 148.52 12.55 1086002 91770 sda1 0.07 0.56 0.00 4120 18 sda2 3.22 147.79 12.55 1080650 91752
11. Display LVM Statistics
With -N (Uppercase) parameter displays only LVM statistics as shown.
[root@tecmint ~]# iostat -N Linux 2.6.32-279.el6.i686 (tecmint.com) 09/03/2012 _i686_ (1 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 0.11 0.01 1.39 1.85 0.00 96.64 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sda 3.20 142.84 12.16 1086002 92466 vg_tecmint-lv_root 5.13 141.68 12.16 1077154 92448 vg_tecmint-lv_swap 0.04 0.34 0.00 2576 0
12. iostat version.
With -V (Uppercase) parameter displays version of iostat as shown.
[root@tecmint ~]# iostat -V sysstat version 9.0.4 (C) Sebastien Godard (sysstat orange.fr)
Note: vmstat and iostat contains number of columns and flags which may not possible to explain in details. If you want to know more about it you may refer man page of vmstat and iostat. Please share it if you find this article is useful through our comment box below.
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