• Home
  • Disclaimer
  • Contact
  • Archives
  • About
  • Subscribe
  • Support
  • Advertise

Kernel Talks

Unix, Linux, & Cloud!

  • How-to guides
    • Howto
    • Disk management
    • Configurations
    • Troubleshooting
  • OS
    • HPUX
    • Linux
  • Miscellaneous
    • Software & Tools
    • Cloud Services
    • System services
    • Virtualization
  • Certification Preparations
    • AWS Certified Solutions Architect – Associate
    • AWS Certified Solutions Architect – Professional
    • AWS Certified SysOps Administrator – Associate
    • AWS Certified Cloud Practitioner
    • Certified Kubernetes Administrator
    • Hashicorp Certified Terraform Associate
    • Oracle Cloud Infrastructure Foundations 2020 – Associate
  • Tips & Tricks
  • Linux commands
You are here: Home / Commands

sar command (Part III) : Disk, Network reporting

Published: December 21, 2016 | Modified: June 20, 2020



Learn System Activity Report sar command with real-world scenario examples. Understand how to do disk, network reporting using this command.

In the last two parts of the sar command, we have seen time formats to be used with command, its data files, CPU & Memory reporting. In this last part, we will be seeing disk, network reporting using sar command.

Read last two parts of this tutorial here :

  • Part I : sar command : All you need to know
  • Part II : CPU & Memory reporting using sar

Disk IO reporting

sar provides disk (block devices)  report with -d option.  Normally, it shows below parameters values (highlighted values are more commonly observed for performance monitoring) :

  • DEV: Block device name. It follows the dev m-n format. M is major and n is a minor number of the block devices.
  • tps: Transfers per second
  • rd_sec/s: Sector reads per second (sector is 512 byte)
  • wr_sec/s: Sector writes per second 
  • avgrq-sz:  average size (in sectors) of the requests that were issued to the device
  • avgqu-sz: average queue length of the requests that were issued to the device
  • await: The average time (in milliseconds) for I/O requests
  • svctm: The average service time (in milliseconds) for I/O requests
  • %util: Percentage  of  CPU  time  during  which  I/O requests were issued to the device
# sar -d 2 3
Linux 2.6.39-200.24.1.el6uek.x86_64 (testsrv2)         12/21/2016      _x86_64_        (4 CPU)

01:20:19 AM       DEV       tps  rd_sec/s  wr_sec/s  avgrq-sz  avgqu-sz     await     svctm     %util
01:20:21 AM    dev8-0      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
01:20:21 AM   dev8-64      3.00      2.00      1.00      1.00      0.00      0.50      0.50      0.15
01:20:21 AM   dev8-32      3.00      2.00      1.00      1.00      0.00      0.50      0.33      0.10
01:20:21 AM  dev252-0      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
01:20:21 AM  dev252-1      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
01:20:21 AM  dev252-2      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00

In the above output, device names are not so user friendly. So to identify devices easily, -p option is available. This option prints pretty device names in the DEV column and it should always be used with -d option.

# sar -d -p 2 3
Linux 2.6.39-200.24.1.el6uek.x86_64 (testsrv2)         12/21/2016      _x86_64_        (4 CPU)

01:20:38 AM       DEV       tps  rd_sec/s  wr_sec/s  avgrq-sz  avgqu-sz     await     svctm     %util
01:20:40 AM       sda      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
01:20:40 AM       sdb      4.98      0.00     91.54     18.40      0.00      0.80      0.20      0.10
01:20:40 AM       sdc      2.99      1.99      1.00      1.00      0.00      0.67      0.67      0.20
01:20:40 AM      dm-0      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
01:20:40 AM      dm-1      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
01:20:40 AM      dm-2      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00

Now see above output where device names are easily identifiable. sda means disk /dev/sda and so on.

Network utilization reporting

Option -n gives all network stats. There are a total of 18 different keywords (like NFS, IP, DEV, TCP, etc.) which can be used with -n option to get related parameters. Each keyword has almost 8-10 parameters to display. So in the call, if you are using ALL keyword, then the output will be a huge list of parameters which is difficult to understand.

To keep it short here we will see only one example of keyword DEV i.e. device. This will show the device i.e. network card’s parameter values. Most of the time NIC performance is checked hence we are using this keyword example.

# sar -n DEV 2 1
Linux 2.6.39-200.24.1.el6uek.x86_64 (textsrv2)         12/21/2016      _x86_64_        (4 CPU)

01:35:22 AM     IFACE   rxpck/s   txpck/s    rxkB/s    txkB/s   rxcmp/s   txcmp/s  rxmcst/s
01:35:24 AM        lo      6.00      6.00      0.29      0.29      0.00      0.00      0.00
01:35:24 AM      eth0     15.50      0.50      0.91      0.04      0.00      0.00      0.00
01:35:24 AM      eth1      6.50      4.50      0.97      0.77      0.00      0.00      0.00
01:35:24 AM      eth3      0.00      0.00      0.00      0.00      0.00      0.00      0.00

Average:        IFACE   rxpck/s   txpck/s    rxkB/s    txkB/s   rxcmp/s   txcmp/s  rxmcst/s
Average:           lo      6.00      6.00      0.29      0.29      0.00      0.00      0.00
Average:         eth0     15.50      0.50      0.91      0.04      0.00      0.00      0.00
Average:         eth1      6.50      4.50      0.97      0.77      0.00      0.00      0.00
Average:         eth3      0.00      0.00      0.00      0.00      0.00      0.00      0.00

In the above example, I used the DEV keyword along with -n option and took only one iteration in output. Parameters displayed for device keyword are :

  • IFACE: Its interface name. You can easily see eth0, eth1, loopback (lo) interfaces here.
  • rxpck/s: Packets received per seconds
  • txpck/s: packets transmitted per second
  • rxkB/s: kilobytes received per second
  • txkB/s : kilobytes transmitted per second
  • rxcmp/s: compressed packets received per second
  • txcmp/s: compressed packets transmitted per second
  • rxmcst/s: Number of multicast packets received per second

This concludes sar command tutorial’s part III about the disk, network reporting. This is a three-part tutorial with example outputs included. Put your queries, suggestions, feedback in the comments below. You can also reach us using our Contact form. 

⇠ Previous article
sar command (Part II) : CPU, Memory reporting
Next article ⇢
How to save top command output in file

Related stuff:

  • How to replay Linux session recorded by the script command
  • sar command (Part II) : CPU, Memory reporting
  • Watch command to execute script/shell command repeatedly
  • How to restart NFS in HPUX
  • Command alias in Linux, Unix
  • Adding extra or secondary swap in HPUX
  • xfs file system commands with examples
  • chage command in Linux for password aging control
  • 14 find command examples for Linux
  • 12 examples of ls command in Linux for daily use
  • bdf command formatted output in hpux
  • sar command (Part I): All you need to know with examples

Filed Under: Commands, HPUX, Linux Tagged With: disk performance by sar, disk utilization using sar, How to use sar command, network performance by sar, network utilization using sar, sar reports for disk, sar reports for network

If you like my tutorials and if they helped you in any way, then

  • Consider buying me a cup of coffee via paypal!
  • Subscribe to our newsletter here!
  • Like KernelTalks Facebook page.
  • Follow us on Twitter.
  • Add our RSS feed to your feed reader.

Share Your Comments & Feedback: Cancel reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Get fresh content from KernelTalks

  • Email
  • Facebook
  • RSS
  • Twitter

Get Linux & Unix stuff right into your mailbox. Subscribe now!

* indicates required

This work is licensed under a CC-BY-NC license · Privacy Policy
© Copyright 2016-2023 KernelTalks · All Rights Reserved.
The content is copyrighted to Shrikant Lavhate & can not be reproduced either online or offline without prior permission.