iostat syntax for disk utilization report

iostat -d -x interval count

-d : Display the device utilization report (d == disk)
-x : Display extended statistics including disk utilization

interval : It is time period in seconds between two samples . iostat 2 will give data at each 2 seconds interval.

count : It is the number of times the data is needed . iostat 2 5 will give data at 2 seconds interval 5 times

Display 3 reports of extended statistics at 5 second intervals for disk

Type the following command:

# iostat -d -x 5 3

Output:

[root@vari Desktop]# iostat -d -x 5 3

Linux 2.6.18-128.7.1.el5xen (vari.taashee.com) 08/26/2009 _i686_ (2 CPU)

Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util

sda 2.41 12.42 3.27 5.37 134.84 142.70 32.13 0.12 14.04 1.83 1.58

Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util

sda 0.00 1.60 0.00 0.40 0.00 16.00 40.00 0.00 0.00 0.00 0.00

Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util

sda 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Where,

rrqm/s : The number of read requests merged per second that were queued to the hard disk
wrqm/s : The number of write requests merged per second that were queued to the hard disk
r/s : The number of read requests per second
w/s : The number of write requests per second
rsec/s : The number of sectors read from the hard disk per second
wsec/s : The number of sectors written to the hard disk per second
avgrq-sz : The average size (in sectors) of the requests that were issued to the device.
avgqu-sz : The average queue length of the requests that were issued to the device
await : The average time (in milliseconds) for I/O requests issued to the device to be served. This includes the time spent by the requests in queue and the time spent servicing them.

svctm : The average service time (in milliseconds) for I/O requests that were issued to the device
%util : Percentage of CPU time during which I/O requests were issued to the device (bandwidth utilization for the device). Device saturation occurs when this value is close to 100%.

How do I interpret the output result for optimization?

First you need to note down following values from the iostat output:

1. The average service time (svctm)
2. Percentage of CPU time during which I/O requests were issued (%util)
3. See if a hard disk reports consistently high reads/writes (r/s and w/s)

If any one of these are high, you need to take one of the following action:

Get high speed disk and controller for file system (for example move from SATA I to SAS 15k disk)
Tune software or application or kernel or file system for better disk utilization
Use RAID array to spread the file system

To extract a cpio file:

cpio -iv < cpio_file

To list the contents of a cpio file:

cpio -itv < cpio_file

To create a cpio file with all files in the current directory:

ls | cpio -o > cpio_file

To extract all files from an RPM:

rpm2cpio RPM_file | cpio -idv

To extract individual file(s) from an RPM:

rpm2cpio RPM_file | cpio -id individual_file(s)

e.g. Extracting libcrypto.so.0.9.7a and libssl.so.0.9.7a from openssl-0.9.7a-2.i386.rpm:

rpm2cpio openssl-0.9.7a-2.i386.rpm | cpio -it egrep “libcrypto.so.0.9.7a|libssl.so.0.9.7a”

-rwxr-xr-x 1 root root 992092 Feb 27 12:10 ./lib/libcrypto.so.0.9.7a
-rwxr-xr-x 1 root root 216004 Feb 27 12:10 ./lib/libssl.so.0.9.7a

rpm2cpio openssl-0.9.7a-2.i386.rpm | cpio -idv ./lib/libssl.so.0.9.7a ./lib/libcrypto.so.0.9.7a

This will extract the two files from the RPM into a ./lib subdirectory.

Lets say you have this package from FC11:

[root@localhost ~]# rpm -q gcc
gcc-4.4.0-4.i586

But you have an source code that needs gcc-4.3 to compile or something lower.

So download lets say this: gcc-4.3.2-7.i386.rpm then:

mkdir newgcc && cd newgcc
download http://pathtogcc/gcc-4.3.2-7.i386.rpm
rpm2cpio gcc-4.3.2-7.i386.rpm | cpio -idv

Now you should have in newgcc/usr/bin/gcc.

Or download the gcc package you need from ftp://ftp.gnu.org and compile it with –prefix=$HOME/newgcc

Under Fedora and Centos:

[root@infra ~]# yum install yum-downloadonly

Be sure /etc/yum.conf contains : plugins=1

[root@infra ~]# yum reinstall gcc –downloadonly –downloaddir=/root
Loaded plugins: downloadonly
Setting up Reinstall Process
Resolving Dependencies
–> Running transaction check
—> Package gcc.i386 0:4.1.2-33 set to be updated
—> Package gcc.i386 0:4.1.2-33 set to be erased
–> Finished Dependency Resolution

Dependencies Resolved

Installing:
gcc i386 4.1.2-33 fedora 5.2 M
Removing:
gcc i386 4.1.2-33 installed 9.6 M

Transaction Summary

Install 1 Package(s)
Update 0 Package(s)
Remove 1 Package(s)

Total download size: 5.2 M
Is this ok [y/N]: y
Downloading Packages:
gcc-4.1.2-33.i386.rpm | 5.2 MB 00:00

exiting because –downloadonly specified

Now /root should contain : gcc-4.1.2-33.i386.rpm

I have Fedora 8 on this server..to install webmin:

yum -y install perl-Net-SSLeay
rpm -ihv http://superb-west.dl.sourceforge.net/sourceforge/webadmin/webmin-1.480-1.noarch.rpm

Then login to the Webmin interface: https://site.com:10000/ and enable Networking -> Bandwidth Monitoring.
It uses iptables and reads counters for IN/OUT. A good practice would be to change the port. This should work on Centos 5.2 / Centos 5.3 too. Also keep in mind that default installations of Fedora or Centos might require to open port 10000. On this Fedora 8 I had to :

iptables -I RH-Firewall-1-INPUT -p tcp -m state –state NEW -m tcp –dport 10000 -j ACCEPT
service iptables save

How to upgrade MySQL 5.0 to MySQL 5.1 in a cPanel server

Login as root and edit /var/cpanel/cpanel.config.

Replace :

mysql-server=5.0 with
mysql-server=5.1

Finally run: /scripts/mysqlup

Centos :

xen-create-image –lvm=lvm1 –hostname=hostname –install-method=rinse –dist=centos-5 –arch=amd64 –ip=ip –netmask=255.255.255.0 –gateway=gw –force –size=80Gb –swap=1024Mb –memory=1024

Debian:

xen-create-image –lvm=lvm1 –hostname=vm01 –install-method=debootstrap –arch=amd64 –ip=ip –netmask=255.255.255.0 –gateway=gw –force –size=80Gb –swap=1024Mb –memory=1024