Follow Techotopia on Twitter

On-line Guides
All Guides
eBook Store
iOS / Android
Linux for Beginners
Office Productivity
Linux Installation
Linux Security
Linux Utilities
Linux Virtualization
Linux Kernel
System/Network Admin
Programming
Scripting Languages
Development Tools
Web Development
GUI Toolkits/Desktop
Databases
Mail Systems
openSolaris
Eclipse Documentation
Techotopia.com
Virtuatopia.com

How To Guides
Virtualization
General System Admin
Linux Security
Linux Filesystems
Web Servers
Graphics & Desktop
PC Hardware
Windows
Problem Solutions

  




 

 

System Administration Guide: Advanced Administration
Previous Next

Displaying Disk Utilization Information (iostat)

Use the iostat command to report statistics about disk input and output, and to produce measures of throughput, utilization, queue lengths, transaction rates, and service time. For a detailed description of this command, refer to the iostat(1M) man page.

How to Display Disk Utilization Information (iostat)

  • You can display disk utilization information by using the iostat command with a time interval in seconds.
    $ iostat 5
         tty          fd0           sd3          nfs1         nfs31          cpu
    tin tout kps tps serv  kps tps serv  kps tps serv  kps tps serv  us sy wt id
      0    1   0   0  410    3   0   29    0   0    9    3   0   47   4  2  0 94

    The first line of output shows the statistics since the last time the system was booted. Each subsequent line shows the interval statistics. The default is to show statistics for the terminal (tty), disks (fd and sd), and CPU (cpu).

Example 13-3 Displaying Disk Utilization Information

The following example shows disk statistics that were gathered every five seconds.

$ iostat 5
tty        sd0           sd6           nfs1         nfs49           cpu
tin tout kps tps serv  kps tps serv  kps tps serv  kps tps serv  us sy wt id
 0    0   1   0   49    0   0    0    0   0    0    0   0   15   0  0  0 100
 0   47   0   0    0    0   0    0    0   0    0    0   0    0   0  0  0 100
 0   16   0   0    0    0   0    0    0   0    0    0   0    0   0  0  0 100
 0   16   0   0    0    0   0    0    0   0    0    0   0    0   0  0  0 100
 0   16  44   6  132    0   0    0    0   0    0    0   0    0   0  0  1 99
 0   16   0   0    0    0   0    0    0   0    0    0   0    0   0  0  0 100
 0   16   0   0    0    0   0    0    0   0    0    0   0    0   0  0  0 100
 0   16   0   0    0    0   0    0    0   0    0    0   0    0   0  0  0 100
 0   16   0   0    0    0   0    0    0   0    0    0   0    0   0  0  0 100
 0   16   0   0    0    0   0    0    0   0    0    0   0    0   0  0  0 100
 0   16   3   1   23    0   0    0    0   0    0    0   0    0   0  0  1 99
 0   16   0   0    0    0   0    0    0   0    0    0   0    0   0  0  0 100
 0   16   0   0    0    0   0    0    0   0    0    0   0    0   0  0  0 100
 0   16   0   0    0    0   0    0    0   0    0    0   0    0   0  0  0 100

The following table describes the fields in the output of the iostat n command.

Device Type

Field Name

Description

Terminal

Device Type

tin

Number of characters in the terminal input queue

tout

Number of characters in the terminal output queue

Disk

Device Type

bps

Blocks per second

tps

Transactions per second

serv

Average service time, in milliseconds

CPU

Device Type

us

In user mode

sy

In system mode

wt

Waiting for I/O

id

Idle

How to Display Extended Disk Statistics (iostat -xtc)

  • Run the iostat -xtc command to display extended disk statistics.
    $ iostat -xtc
                      extended device statistics                      tty         cpu
    device       r/s    w/s   kr/s   kw/s wait actv  svc_t  %w  %b  tin tout  us sy wt id
    fd0          0.0    0.0    0.0    0.0  0.0  0.0    0.0   0   0    0    0   0  0  0 100
    sd0          0.0    0.0    0.4    0.4  0.0  0.0   49.5   0   0 
    sd6          0.0    0.0    0.0    0.0  0.0  0.0    0.0   0   0 
    nfs1         0.0    0.0    0.0    0.0  0.0  0.0    0.0   0   0 
    nfs49        0.0    0.0    0.0    0.0  0.0  0.0   15.1   0   0 
    nfs53        0.0    0.0    0.4    0.0  0.0  0.0   24.5   0   0 
    nfs54        0.0    0.0    0.0    0.0  0.0  0.0    6.3   0   0 
    nfs55        0.0    0.0    0.0    0.0  0.0  0.0    4.9   0   0 

    The iostat -xtc command displays a line of output for each disk. The output fields are described in the following list.

    r/s

    Reads per second

    w/s

    Writes per second

    kr/s

    Kbytes read per second

    kw/s

    Kbytes written per second

    wait

    Average number of transactions that are waiting for service (queue length)

    actv

    Average number of transactions that are actively being serviced

    svc_t

    Average service time, in milliseconds

    %w

    Percentage of time that the queue is not empty

    %b

    Percentage of time that the disk is busy

Previous Next

 
 
  Published under the terms fo the Public Documentation License Version 1.01. Design by Interspire