Being the administrator of a large Linux shop, I have had to extend the filesystems on the Red Hat Linux server a few times. Each time I had the opportunity to extend the filesystem, I found that I struggled to remember the commands and steps. This is because Linx is a very command line driven operating system. All right that is not completely true anymore, some variants of Linux have graphical interfaces. Such as Red Hat has the graphical Logical Volume Manager (LVM), but I find the LVM to be buggy and unreliable at times. Personally I find it more reliable and easier to extend the filesystem using the command line interface.<\/p>\n
The sequence to extend the filesystem is as follow.<\/strong> (2) Partition the new disk space using fdisk.<\/p>\n (3) Initialize the new partition, using the command pvcreate. Run partprobe to update the kernel.<\/p>\n (4) Extend the existing volume group with the new partition using the command vgextend.<\/p>\n (5) Extend the existing logical volume group using lvextend.<\/p>\n (6) Grow the filesystem with the command resize2fs.<\/p>\n Take a snapshot of the existing disks and to understand how they are partitioned.<\/strong> \n[root@linux_server ~]# fdisk -l<\/p>\n Disk \/dev\/sda: 10.7 GB, 10737418240 bytes ice Boot Start End Blocks Id System Disk \/dev\/sdb: 21.4 GB, 21475491840 bytes ice Boot Start End Blocks Id System You also need to take a snapshot of how the partitions are allocated to the volume groups. In the below example, the result of pvscan indicates that sda2 is mapped to the volume group VolGroup00. But where is sda1? Well sda1 is mapped to the \/boot filesystem, you will see it when you issue the mount command. You can also use the command pvs or pvdisplay instead of pvscan.<\/p>\n [root@linux_server ~]# pvscan The mount command will show you that \/dev\/sda1 is mounted as \/boot. In this example we will be extending the \/ (root) filesystem.<\/p>\n [root@linux_server ~]# mount Add the new disk or extend the existing disk in Vmware.<\/strong> Partition the disk<\/strong> [root@linux_server ~]# fdisk \/dev\/sda<\/p>\n The number of cylinders for this disk is set to 2610. Command (m for help): m (select m to display the help screen)<\/strong> Command (m for help): n (select n to add a new partition)<\/strong><\/p>\n Command action First cylinder (1306-2610, default 1306): (hit the enter key to accept the default)<\/strong>
\n(1) Add the new disk. In my case I was running Red Hat Enterprise 5 Linux as a guest operating system in Vmware ESX server. I simply had to increase the disk size using the Vmware Vcenter interface, under edit setting, disk provisioning. You will need to reboot the guest OS after to recognize the new disk size.<\/p>\n
\nThe fdisk command will display the configuration of the existing disks. In this example there are two disks, a 10.7 GB \/dev\/sda and \/dev\/sdb which is 21.4 GB. Disk sda has two partitions, sda1 and sda2. The second disk sdb has only one partition sdb1.<\/p>\n
\n255 heads, 63 sectors\/track, 1305 cylinders
\nUnits = cylinders of 16065 * 512 = 8225280 bytes<\/p>\n
\n\/dev\/sda1 * 1 13 104391 83 Linux
\n\/dev\/sda2 14 1305 10377990 8e Linux LVM<\/p>\n
\n255 heads, 63 sectors\/track, 2610 cylinders
\nUnits = cylinders of 16065 * 512 = 8225280 bytes<\/p>\n
\n\/dev\/sdb1 1 2610 20964793+ 8e Linux LVM<\/p><\/blockquote>\n
\n PV \/dev\/sdb1 VG gfs_vg lvm2 [19.99 GB \/ 8.99 GB free]
\n PV \/dev\/sda2 VG VolGroup00 lvm2 [9.88 GB \/ 0 free]
\n Total: 2 [29.84 GB] \/ in use: 2 [29.84 GB] \/ in no VG: 0 [0 ]<\/p><\/blockquote>\n
\n\/dev\/mapper\/VolGroup00-LogVol00 on \/ type ext3 (rw)
\nproc on \/proc type proc (rw)
\nsysfs on \/sys type sysfs (rw)
\ndevpts on \/dev\/pts typepts (rw,gid=5,mode=620)
\n\/dev\/sda1 on \/boot type ext3 (rw)
\ntmpfs on \/dev\/shm type tmpfs (rw)
\nnone on \/proc\/sys\/fs\/binfmt_misc type binfmt_misc (rw)
\nsunrpc on \/var\/lib\/nfs\/rpc_pipefs type rpc_pipefs (rw)
\nnone on \/sys\/kernel\/config type configfs (rw)
\n\/dev\/mapper\/gfs_vg-gfs_lv on \/mnt\/gfs type gfs2 (rw,noatime,nodiratime,hostdata=jid=0:id=196609:first=0)<\/p><\/blockquote>\n
\nExpand the disk sda using the VMware Vcenter management console. Under the summary tab of the guest server, go to edit settings \u2013 disk provisioning. Simply increase the disk size and then reboot the guest OS.<\/p>\n
\nAfter the guest server has been rebooted it should see the size increment in sda. You now need to partition the new disk space using the command fdisk.<\/p>\n
\nThere is nothing wrong with that, but this is larger than 1024,
\nand could in certain setups cause problems with:
\n1) software that runs at boot time (e.g., old versions of LILO)
\n2) booting and partitioning software from other OSs
\n (e.g., DOS FDISK, OS\/2 FDISK)<\/p>\n
\nCommand action
\n a toggle a bootable flag
\n b edit bsd disklabel
\n c toggle the dos compatibility flag
\n d delete a partition
\n l list known partition types
\n m print this menu
\n n add a new partition
\n o create a new empty DOS partition table
\n p print the partition table
\n q quit without saving changes
\n s create a new empty Sun disklabel
\n t change a partition\u2019s system id
\n u change display\/entry units
\n v verify the partition table
\n w write table to disk and exit
\n x extra functionality (experts only)<\/p>\n
\n e extended
\n p primary partition (1-4)
\np (select p to create a primary partition)<\/strong>
\nPartition number (1-4): 3 (enter 3 for partition number, we already know from the output of fdisk -l that sda1 and sda2 already exist, therefore the new partition will be sda3)<\/p>\n
\nUsing default value 1306
\nLast cylinder or +size or +sizeM or +sizeK (1306-2610, default 2610): (press the enter key to accept the default. You can also select something lower than 2610, if you do not want to use all available free disk space)<\/strong>
\nUsing default value 2610<\/p>\n