Adding Additional Disk Drives to CentOS 5/6
Adding a new drive to CentOS or RedHat systems.
Making use of a second drive for extra space? Here's a quick run-down:
1) Make sure you know which disk is being formatted. First, second, and third drives will be /dev/sda, /dev/sdb, and /dev/sdc respectively. Check this with
[03:50:04] [root@virt ~]# fdisk -l Disk /dev/sda: 34.3 GB, 34359738368 bytes 255 heads, 63 sectors/track, 4177 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sda1 * 1 13 104391 83 Linux /dev/sda2 14 4177 33447330 8e Linux LVM Disk /dev/sdb: 8589 MB, 8589934592 bytes 255 heads, 63 sectors/track, 1044 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk /dev/sdb doesn't contain a valid partition table
2) You can see that /dev/sdb (our second hard drive) does not have any partitions. We will need to create a partition(s) on the drive and then make a file system on it, then mount it. Let's write partitions to the drive using
[03:53:01] [root@virt ~]# fdisk /dev/sdb Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel Building a new DOS disklabel. Changes will remain in memory only, until you decide to write them. After that, of course, the previous content won't be recoverable. Command (m for help): m Command action a toggle a bootable flag b edit bsd disklabel c toggle the dos compatibility flag d delete a partition l list known partition types m print this menu n add a new partition o create a new empty DOS partition table p print the partition table q quit without saving changes s create a new empty Sun disklabel t change a partition's system id u change display/entry units v verify the partition table w write table to disk and exit x extra functionality (experts only) Command (m for help):
3) As you can see from the help menu (by using the command "m") we want to add a new partition. Using the defaults will use the entire disk. After it's created, you will want to use the command "w" to "write table to disk and exit".
Command (m for help): n Command action e extended p primary partition (1-4) p Partition number (1-4): 1 First cylinder (1-1044, default 1): 1 Last cylinder or +size or +sizeM or +sizeK (1-1044, default 1044): Using default value 1044 Command (m for help): w The partition table has been altered! Calling ioctl() to re-read partition table. Syncing disks. [03:54:58] [root@virt ~]#
4) Now you will notice that the output of
fdisk -l /dev/sdb shows a partition as /dev/sdb1:
[03:57:08] [root@virt ~]# fdisk -l /dev/sdb Disk /dev/sdb: 8589 MB, 8589934592 bytes 255 heads, 63 sectors/track, 1044 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sdb1 1 1044 8385898+ 83 Linux
5) Now we need to create a file system on it. I've always used ext3 for general use/purposes. You'll want to use the command
mkfs -t ext3 /dev/sdb1 as shown here:
[03:58:38] [root@virt ~]# mkfs -t ext3 /dev/sdb1 mke2fs 1.39 (29-May-2006) Filesystem label= OS type: Linux Block size=4096 (log=2) Fragment size=4096 (log=2) 1048576 inodes, 2096474 blocks 104823 blocks (5.00%) reserved for the super user First data block=0 Maximum filesystem blocks=2147483648 64 block groups 32768 blocks per group, 32768 fragments per group 16384 inodes per group Superblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632 Writing inode tables: done Creating journal (32768 blocks): done Writing superblocks and filesystem accounting information: done This filesystem will be automatically checked every 38 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override.
6) Great, now we have a single partitioned secondary drive using ext3 file system. Now you want to create a directory to mount it in; lets just use "/drive2". You'll need to use the command
mount -t [filesystem] [source] [mount directory] to mount it.
[03:59:50] [root@virt ~]# mount -t ext3 /dev/sdb1 /drive2/
7) Now you'll notice, via df, that the drive is mounted:
[03:59:57] [root@virt ~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/VolGroup00-LogVol00 28G 1.4G 25G 6% / /dev/sda1 99M 19M 76M 20% /boot tmpfs 1014M 0 1014M 0% /dev/shm /dev/sdb1 7.9G 147M 7.4G 2% /drive2
8) Last step - you want to make sure the drive automatically mounts itself when the server boots/reboots. You'll need to add the following line to your
/dev/sdb1 /drive2 ext3 defaults 0 0