How to format and mount second hard drive on Linux

If you have two hard drives you can mount second hard drive to be used for (cPanel/WHM) backups or for hosting more sites. The hard drives must not be in any kind of Raid setup. Process of partitioning, formatting and mounting is quite simple.

First check what disk drives do you have. Usually disk drives on Linux are named /dev/sda (first HDD), /dev/sdb (second HDD) or something similar.
You can get a list of disk drives in system using this command

fdisk -l | grep '^Disk'

The output should be something like this:

Disk /dev/sdb: 500.1 GB, 500107862016 bytes
Disk /dev/sda: 500.1 GB, 500107862016 bytes

So those are two 500 GB hard drives…

If you execute command like the one below you’ll get more detailed preview of your hard discs and their partitions:

fdisk -l

Output should looks like this:

Disk /dev/sdb: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x1c7e861c

Disk /dev/sdb doesn't contain a valid partition table

Disk /dev/sda: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00080071

Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          14      104448   83  Linux
/dev/sda2              14         144     1048576   82  Linux swap / Solaris
/dev/sda3             144       60802   487232512   83  Linux

You should notice that second hard disk (/dev/sdb) has no partition and that probably means that it’s un-partitioned yet.

So let’s make the partition on /dev/sdb by executing

fdisk /dev/sdb

and then use following in the prompt
– “n” for new partion
– “p” for primary partition
– “1” for the first partition
– “Enter” / “Enter” for the first AND last cylinders (automatically use the entire disk)
– “w” to save what I have done

That has created and saved new partition and it will be called /dev/sdb1 (first partition on /dev/sdb). Next step is to format it.

mkfs.ext3 /dev/sdb1

On newer distributions (CentOS 6.3 for eg) use this command to format a new partition.

mkfs -t ext3 /dev/sdb1

If you want to use this hard disk for backup make /backup folder or if you want to use it to store more sites make new home folder called /home2

mkdir /backup
mkdir /home2

Now just mount the backup partition or the new home partition

mount /dev/sdb1 /backup
mount /dev/sdb1 /home2

Now you can use the additional hard drive for cPanel/WHM backups or storing new sites. cPanel should automatically detect /home2 and should ask you whether you like to setup new account on /home or at /home2.

If you want the partition to auto mount on server (re)boot edit fstab file located at /etc/fstab and add one of following lines at the bottom of it depending if you for /backup folder or the line below for /home2 folder:

/dev/sdb1   /backup   ext3   defaults   0   0
/dev/sdb1   /home2    ext3   defaults   0   0

Note: After adding one of these lines press add one more empty line below since fstab requires the new line symbol at the end of every config line. Before you issue the following command, be aware that this re-mounts ALL Filesystems, and will more than likely disconnect most other users

To make sure this mounts automatically, issue the following command:

mount -a

If you got no errors – your mount worked, try df -h once more to see if everything is fine.

Tags: format linux hard drive in centos

How to raise ServerLimit and MaxClient

If your server starts getting more and more traffic you’ll need to lift up number of allowed Apache connections. This guide works only on cPanel/WHM powered servers.

The easy way
Log in at WHM and to go to Service Configuration > Apache Configuration > Global Configuration. In there find ServerLimit and MaxClients and set those to some nice value (eg. 1024 or 2048 depends how much memory you have). Save and that should be it.

The geek way
Edit of httpd.conf (usually located at /usr/local/apache/conf folder). It should look something like this (depending on your server specification):

StartServers        5
MinSpareServers     5
MaxSpareServers     10
ServerLimit         1024
MaxClients          1024
MaxRequestsPerChild 10000

Save, Distill settings, restart Apache:

/usr/local/cpanel/bin/apache_conf_distiller --update
/scripts/rebuildhttpdconf
/etc/init.d/httpd restart

Check
After you do something like this you simply MUST take a look at your Apache error_log file (usually located at /usr/local/apache/logs folder). If you see following line in Apache error_log:

** [warn] WARNING: Attempt to change ServerLimit ignored during restart

You should stop and run the Apache again since ServerLimit can’t be changed by restarting Apache. To do so execute following at SSH:

apachectl stop
apachectl start
Tags: serverlimit, apache serverlimit, WARNING: Attempt to change ServerLimit ignored during restart, serverlimit maxclients, serverlimit vs maxclients, serverlimit apache