Adding a New Disk Drive to an Ubuntu Linux System
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One of the first problems encountered by users these days is that they run out of disk space to store data. Fortunately disk space is now one of the cheapest of all IT commodities. In this chapter we will look at the steps necessary to integrate a new disk drive into an Ubuntu system.
Getting Started
This tutorial assumes that the new physical hard drive has been installed on the system and is visible to the operating system. The best way to do this is to enter the system BIOS setup during the boot process and ensure that the BIOS sees the disk drive. Sometimes the BIOS will provide a menu option to scan for new drives. If the BIOS does not see the disk drive double check the connectors and jumper settings (if any) on the drive.
Finding the New Hard Drive in Ubuntu
Assuming the drive is visible to the BIOS it should automatically be detected by the operating system. Typically, the disk drives in a system are assigned device names beginning hd or sd followed by a letter to indicate the device number. For example, the first device might be /dev/sda, the second /dev/sdb and so on.
The following is output from a system with only one physical disk drive:
ls /dev/sd* /dev/sda /dev/sda1 /dev/sda2 /dev/sda5
This shows that the disk drive represented by /dev/sda is itself divided into three partitions, represented by /dev/sda1, /dev/sda2 and /dev/sda5.
The following output is from the same system after a second hard disk drive has been installed and detected by the operating system:
ls /dev/sd* /dev/sda /dev/sda1 /dev/sda2 /dev/sda5 /dev/sdb
As shown above, the new hard drive has been assigned to the device file /dev/sdb. At this point the drive has no partitions shown (because we have yet to create any).
Creating Linux Partitions
The next step is to create one or more Linux partitions on the new disk drive. This is achieved using the fdisk utility which takes as a command-line argument the device to be partitioned (in this case /dev/sdb):
sudo fdisk /dev/sdb [sudo] password for johndoe: Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel Building a new DOS disklabel with disk identifier 0xc2fe324b. Changes will remain in memory only, until you decide to write them. After that, of course, the previous content won't be recoverable. Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite) Command (m for help):
In order to view the current partitions on the disk enter the p command:
Command (m for help): p Disk /dev/sdb: 2147 MB, 2147483648 bytes 255 heads, 63 sectors/track, 261 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk identifier: 0xc2fe324b Device Boot Start End Blocks Id System
As we can see from the above fdisk output, the disk currently has no partitions because it is a previously unused disk. The next step is to create a new partition on the disk, a task which is performed by entering n (for new partition) and p (for primary partition):
Command (m for help): n Command action e extended p primary partition (1-4) p Partition number (1-4):
In this example we only plan to create one partition which will be partition 1. Next we need to specify where the partition will begin and end. Since this is the first partition we need it to start at cylinder 1 and since we want to use the entire disk we specify the last cylinder as the end. Note that if you wish to create multiple partitions you can specify the size of each partition by cylinders, bytes, kilobytes or megabytes.
Partition number (1-4): 1 First cylinder (1-261, default 1): Using default value 1 Last cylinder or +size or +sizeM or +sizeK (1-261, default 261): Using default value 261
Now that we have specified the partition we need to write it to the disk using the w command:
Command (m for help): w The partition table has been altered! Calling ioctl() to re-read partition table. Syncing disks.
If we now look at the devices again we will see that the new partition is visible as /dev/sdb1:
ls /dev/sd* /dev/sda /dev/sda1 /dev/sda2 /dev/sda5 /dev/sdb /dev/sdb1
Now that the disk has been successfully partitioned, the next step is to create a file system on our new partition.
Creating a Filesystem on an Ubuntu Disk Partition
We now have a new disk installed, it is visible to Ubuntu and we have configured a Linux partition on the disk. The next step is to create a Linux file system on the partition so that the operating system can use it to store files and data. The easiest way to create a file system on a partition is to use the mkfs.ext3 utility which takes as arguments the label and the partition device:
sudo mkfs.ext3 -L /photos /dev/sdb1
mke2fs 1.40.2 (12-Jul-2007)
Filesystem label=/photos
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
262144 inodes, 524112 blocks
26205 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=536870912
16 block groups
32768 blocks per group, 32768 fragments per group
16384 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912
Writing inode tables: done
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 28 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
Mounting a Filesystem
Now that we have created a new file system on the Linux partition of our new disk drive we need to mount it so that it is accessible. In order to do this we need to create a mount point. A mount point is simply a directory into which the file system will be mounted. For the purposes of this example we will create a /photos directory to match our file system label (although it is not necessary that these values match):
sudo mkdir /photos
The file system may then be manually mounted using the mount command:
sudo mount /dev/sdb1 /photos
Running the mount command with no arguments shows us all currently mounted file systems (including our new file system):
mount /dev/sda1 on / type ext3 (rw,errors=remount-ro) proc on /proc type proc (rw,noexec,nosuid,nodev) /sys on /sys type sysfs (rw,noexec,nosuid,nodev) varrun on /var/run type tmpfs (rw,noexec,nosuid,nodev,mode=0755) varlock on /var/lock type tmpfs (rw,noexec,nosuid,nodev,mode=1777) udev on /dev type tmpfs (rw,mode=0755) devshm on /dev/shm type tmpfs (rw) devpts on /dev/pts type devpts (rw,gid=5,mode=620) lrm on /lib/modules/2.6.22-14-generic/volatile type tmpfs (rw) securityfs on /sys/kernel/security type securityfs (rw) /dev/sdb1 on /photos type ext3 (rw)
Configuring Ubuntu to Automatically Mount a Filesystem
In order to set up the system so that the new file system is automatically mounted at boot time, an entry needs to be added to the /etc/fstab file. This may be edited by issuing the following command in a terminal window:
sudo gedit /etc/fstab
The following example shows an /etc/fstab file configured to automount our /photos partition:
# /etc/fstab: static file system information. # # <file system> <mount point> <type> <options> <dump> <pass> proc /proc proc defaults 0 0 # /dev/sda1 UUID=4a621e4d-8c8b-4b39-8934-98ab8aa52ebc / ext3 defaults,errors=remount-ro 0 1 # /dev/sda5 UUID=9c82bf09-c6f7-4042-8927-34e46518b224 none swap sw 0 0 /dev/scd0 /media/cdrom0 udf,iso9660 user,noauto,exec 0 0 /dev/fd0 /media/floppy0 auto rw,user,noauto,exec 0 0 /dev/sdb1 /photos auto defaults 0 0
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