Chapter 12. Managing Disk Storage
Introduction to different methods........
12.1. Standard Partitions using
Many users need to view the existing partition table, change the size of the partitions, remove partitions, or add partitions from free space or additional hard drives. The utility
partedallows users to perform these tasks. This chapter discusses how to use
partedto perform file system tasks.
If you want to view the system's disk space usage or monitor the disk space usage, refer to Section 39.3, “File Systems”.
You must have the
partedpackage installed to use the
partedutility. To start
parted, at a shell prompt as root, type the command
parted /dev/sda, where /dev/sda is the device name for the drive you want to configure. The
(parted)prompt is displayed. Type
helpto view a list of available commands.
If you want to create, remove, or resize a partition, the device cannot be in use (partitions cannot be mounted, and swap space cannot be enabled). The partition table should not be modified while in use because the kernel may not properly recognize the changes. Data could be overwritten by writing to the wrong partition because the partition table and partitions mounted do not match. The easiest way to achieve this it to boot your system in rescue mode. Refer to Chapter 5, Basic System Recovery for instructions on booting into rescue mode. When prompted to mount the file system, select Skip.
Alternately, if the drive does not contain any partitions in use (system processes that use or lock the file system from being unmounted), you can unmount them with the
umountcommand and turn off all the swap space on the hard drive with the
Table 12.1, “
partedcommands” contains a list of commonly used
partedcommands. The sections that follow explain some of them in more detail.
| ||Perform a simple check of the file system|
| ||Copy file system from one partition to another; from and to are the minor numbers of the partitions|
| ||Display list of available commands|
| ||Create a disk label for the partition table|
| ||Create a file system of type file-system-type|
| ||Make a partition without creating a new file system|
| ||Make a partition and create the specified file system|
| ||Move the partition|
| ||Name the partition for Mac and PC98 disklabels only|
| ||Display the partition table|
| || Quit |
| ||Rescue a lost partition from start-mb to end-mb|
| ||Resize the partition from start-mb to end-mb|
| ||Remove the partition|
| ||Select a different device to configure|
| ||Set the flag on a partition; state is either on or off|
12.1.1. Viewing the Partition Table
parted, type the following command to view the partition table:
A table similar to the following appears:
Disk geometry for /dev/sda: 0.000-8678.789 megabytes Disk label type: msdos Minor Start End Type Filesystem Flags 1 0.031 101.975 primary ext3 boot 2 101.975 5098.754 primary ext3 3 5098.755 6361.677 primary linux-swap 4 6361.677 8675.727 extended 5 6361.708 7357.895 logical ext3 Disk geometry for /dev/hda: 0.000-9765.492 megabytes Disk label type: msdos Minor Start End Type Filesystem Flags 1 0.031 101.975 primary ext3 boot 2 101.975 611.850 primary linux-swap 3 611.851 760.891 primary ext3 4 760.891 9758.232 extended lba 5 760.922 9758.232 logical ext3
The first line displays the size of the disk, the second line displays the disk label type, and the remaining output shows the partition table.
In the partition table, the Minor number is the partition number. For example, the partition with minor number 1 corresponds to
/dev/sda1. The Start and End values are in megabytes. The Type is one of primary, extended, or logical. The Filesystem is the file system type, which can be one of ext2, ext3, fat16, fat32, hfs, jfs, linux-swap, ntfs, reiserfs, hp-ufs, sun-ufs, or xfs. The Flags column lists the flags set for the partition. Available flags are boot, root, swap, hidden, raid, lvm, or lba.
In this example, minor number 1 refers to the
/boot/file system, minor number 2 refers to the root file system (
/), minor number 3 refers to the swap, and minor number 5 refers to the
12.1.2. Creating a Partition
Do not attempt to create a partition on a device that is in use.
Before creating a partition, boot into rescue mode (or unmount any partitions on the device and turn off any swap space on the device).
parted, where /dev/sda is the device on which to create the partition:
View the current partition table to determine if there is enough free space:
If there is not enough free space, you can resize an existing partition. Refer to Section 12.1.4, “Resizing a Partition” for details.
18.104.22.168. Making the Partition
From the partition table, determine the start and end points of the new partition and what partition type it should be. You can only have four primary partitions (with no extended partition) on a device. If you need more than four partitions, you can have three primary partitions, one extended partition, and multiple logical partitions within the extended. For an overview of disk partitions, refer to the appendix An Introduction to Disk Partitions in the Installation Guide.
For example, to create a primary partition with an ext3 file system from 1024 megabytes until 2048 megabytes on a hard drive type the following command:
mkpart primary ext3 1024 2048
If you use the
mkpartfscommand instead, the file system is created after the partition is created. However,
parteddoes not support creating an ext3 file system. Thus, if you wish to create an ext3 file system, use
mkpartand create the file system with the
mkfscommand as described later.
mkpartfsworks for file system type linux-swap.
The changes start taking place as soon as you press Enter, so review the command before executing to it.
After creating the partition, use the
to make sure the kernel recognizes the new partition.
22.214.171.124. Formating the Partition
The partition still does not have a file system. Create the file system:
/sbin/mkfs -t ext3 /dev/sda6
Formatting the partition permanently destroys any data that currently exists on the partition.
126.96.36.199. Labeling the Partition
Next, give the partition a label. For example, if the new partition is
/dev/sda6and you want to label it
e2label /dev/sda6 /work
By default, the installation program uses the mount point of the partition as the label to make sure the label is unique. You can use any label you want.
188.8.131.52. Creating the Mount Point
As root, create the mount point:
184.108.40.206. Add to
As root, edit the
/etc/fstabfile to include the new partition. The new line should look similar to the following:
LABEL=/work /work ext3 defaults 1 2
The first column should contain
LABEL=followed by the label you gave the partition. The second column should contain the mount point for the new partition, and the next column should be the file system type (for example, ext3 or swap). If you need more information about the format, read the man page with the command
If the fourth column is the word
defaults, the partition is mounted at boot time. To mount the partition without rebooting, as root, type the command:
12.1.3. Removing a Partition
Do not attempt to remove a partition on a device that is in use.
Before removing a partition, boot into rescue mode (or unmount any partitions on the device and turn off any swap space on the device).
parted, where /dev/sda is the device on which to remove the partition:
View the current partition table to determine the minor number of the partition to remove:
Remove the partition with the command
rm. For example, to remove the partition with minor number 3:
The changes start taking place as soon as you press Enter, so review the command before committing to it.
After removing the partition, use the
to make sure the kernel knows the partition is removed.
The last step is to remove it from the
/etc/fstabfile. Find the line that declares the removed partition, and remove it from the file.
12.1.4. Resizing a Partition
Do not attempt to resize a partition on a device that is in use.
Before resizing a partition, boot into rescue mode (or unmount any partitions on the device and turn off any swap space on the device).
parted, where /dev/sda is the device on which to resize the partition:
View the current partition table to determine the minor number of the partition to resize as well as the start and end points for the partition:
The used space of the partition to resize must not be larger than the new size.
To resize the partition, use the
resizecommand followed by the minor number for the partition, the starting place in megabytes, and the end place in megabytes. For example:
resize 3 1024 2048
After resizing the partition, use the
After rebooting the system into normal mode, use the command
dfto make sure the partition was mounted and is recognized with the new size.