5.9.5. Mounting File Systems Automatically with /etc/fstab
When a Red Hat Enterprise Linux system is newly-installed, all the disk partitions defined and/or created during the installation are configured to be automatically mounted whenever the system boots. However, what happens when additional disk drives are added to a system after the installation is done? The answer is «nothing» because the system was not configured to mount them automatically. However, this is easily changed.
The answer lies in the /etc/fstab file. This file is used to control what file systems are mounted when the system boots, as well as to supply default values for other file systems that may be mounted manually from time to time. Here is a sample /etc/fstab file:
LABEL=/ / ext3 defaults 1 1 /dev/sda1 /boot ext3 defaults 1 2 /dev/cdrom /mnt/cdrom iso9660 noauto,owner,kudzu,ro 0 0 /dev/homedisk /home ext3 defaults 1 2 /dev/sda2 swap swap defaults 0 0 File system specifier — For disk-based file systems, either a device file name ( /dev/sda1 ), a file system label specification ( LABEL=/ ), or a devlabel -managed symbolic link ( /dev/homedisk )
Mount point — Except for swap partitions, this field specifies the mount point to be used when the file system is mounted ( /boot )
File system type — The type of file system present on the specified device (note that auto may be specified to select automatic detection of the file system to be mounted, which is handy for removable media units such as diskette drives)
Mount options — A comma-separated list of options that can be used to control mount ‘s behavior ( noauto,owner,kudzu )
Dump frequency — If the dump backup utility is used, the number in this field controls dump ‘s handling of the specified file system
File system check order — Controls the order in which the file system checker fsck checks the integrity of the file systems
Chapter 8. Managing Disk Storage
If you want to view the system’s disk space usage or monitor the disk space usage, refer to Section 42.3, “File Systems”.
By default, the parted package is included when installing Red Hat Enterprise Linux. To start parted , log in as root and type the command parted /dev/sda at a shell prompt (where /dev/sda is the device name for the drive you want to configure).
If you want to remove or resize a partition, the device on which that partition resides must not be in use. Creating a new partition on a device which is in use—while possible—is not recommended.
For a device to not be in use, none of the partitions on the device can be mounted, and any swap space on the device must not be enabled.
As well, the partition table should not be modified while it is in use because the kernel may not properly recognize the changes. If the partition table does not match the actual state of the mounted partitions, information could be written to the wrong partition, resulting in lost and overwritten data.
The easiest way to achieve this is to boot your system in 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 umount command and turn off all the swap space on the hard drive with the swapoff command.
Table 8.1, “ parted commands” contains a list of commonly used parted commands. The sections that follow explain some of these commands and arguments in more detail.
Table 8.1. parted commands
| Command | Description |
|---|---|
| check minor-num | Perform a simple check of the file system |
| cp from to | Copy file system from one partition to another; from and to are the minor numbers of the partitions |
| help | Display list of available commands |
| mklabel label | Create a disk label for the partition table |
| mkfs minor-num file-system-type | Create a file system of type file-system-type |
| mkpart part-type fs-type start-mb end-mb | Make a partition without creating a new file system |
| mkpartfs part-type fs-type start-mb end-mb | Make a partition and create the specified file system |
| move minor-num start-mb end-mb | Move the partition |
| name minor-num name | Name the partition for Mac and PC98 disklabels only |
| Display the partition table | |
| quit | Quit parted |
| rescue start-mb end-mb | Rescue a lost partition from start-mb to end-mb |
| resize minor-num start-mb end-mb | Resize the partition from start-mb to end-mb |
| rm minor-num | Remove the partition |
| select device | Select a different device to configure |
| set minor-num flag state | Set the flag on a partition; state is either on or off |
| toggle [NUMBER [FLAG] | Toggle the state of FLAG on partition NUMBER |
| unit UNIT | Set the default unit to UNIT |
8.1.1. Viewing the Partition Table
After starting parted , use the command print to view the partition table. A table similar to the following appears:
Model: ATA ST3160812AS (scsi) Disk /dev/sda: 160GB Sector size (logical/physical): 512B/512B Partition Table: msdos Number Start End Size Type File system Flags 1 32.3kB 107MB 107MB primary ext3 boot 2 107MB 105GB 105GB primary ext3 3 105GB 107GB 2147MB primary linux-swap 4 107GB 160GB 52.9GB extended root 5 107GB 133GB 26.2GB logical ext3 6 133GB 133GB 107MB logical ext3 7 133GB 160GB 26.6GB logical lvm
The first line contains the disk type, manufacturer, model number and interface, and the second line displays the disk label type. The remaining output below the fourth line 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. Valid Type are metadata, free, primary, extended, or logical. The Filesystem is the file system type, which can be any of the following: