Fedora Linux

have been used: the volume group is main, and the logical volumes are named root, home, and swap.

If you used the Fedora default names, the main volume group will be named VolGroup00, and the logical volumes will be named LogVol00, LogVol01, and so forth.

Although you can increase or decrease the size of any logical volume at any time, an ext3 filesystem within a logical volume can be reduced in size only when it is not in use (unmounted). If the filesystem is the root filesystem, it is in use whenever the system is running; therefore, the only way to shrink the root filesystem is to use another disk as a temporary root filesystem, which is usually done by running the system from the installation CD in rescue mode (see Lab 10.6, 'Using Rescue Mode on an Installation Disc '). There is also a limit to how large a filesystem can grow while in use; growing the filesystem past that point must be done when the filesystem is unmounted.

6.1.1.1. Managing LVM graphically

Start the LVM administration tool by selecting System>Administration>Logical Volume Management. After you enter the root password, the three-panel display shown in Figure 6-1 will appear.

Figure 6-1. Logical Volume Management window

The left pane displays a list of the elements managed by LVM, the middle pane displays the current element in visual form, and the right pane displays a description of the current element.

The element list in the left pane is a collapsing outline. To view the elements within a particular category, click on the small arrow to the left of the category name to rotate it to a downward-pointing position; the elements within that category will be listed immediately below it. For example, to see the logical volumes within the main volume group ( VolGroup00 if you used the default Fedora configuration), click on the arrow beside 'main Logical View' (or 'VolGroup00 Logical View'), and a list of volume groups will appear beneath that line.

The initial display shows the physical (red) and logical (blue) views of the last volume group listed. If you click on a logical volume in the Logical View, the corresponding areas in the physical view are highlighted, as shown in Figure 6-2 .

Figure 6-2. Viewing the location of LV data within PVs

6.1.1.1.1. Growing a logical volume

To increase the size of a logical volume and the filesystem contained in it, select that LV in the lefthand pane, and then click Edit Properties. A properties dialog like the one in Figure 6-3 will appear.

Figure 6-3. LVM properties dialog

Change the unit control from Extents to Gigabytes or Megabytes so that the LV size is displayed in meaningful units; then click on the horizontal slider and drag it to the desired size (or type the size into the 'LV size' field or click 'Use Remaining').

Click OK. The LV will be resized, then the filesystem will be resized, and then the LVM information will be reloaded to update the display. On most systems, this will take just a few seconds.

If the resize fails with the message 'No space left on device,' you may have attempted to resize the filesystem past the maximum that can be done while the filesystem is mounted (in use). You can attempt to unmount the filesystem by deselecting the checkbox labeled Mount and then retry the operation (this will always fail for the root filesystem and will usually fail for filesystems containing /var and /home, in which case you may need to use single-user mode).

6.1.1.2. Shrinking a logical volume

Shrinking a logical volume using the graphical tool is done exactly the same way as growing it: select the LV you wish to resize, click Edit Properties, enter the new size, and click OK.

The catch is that logical volumes containing ext3 filesystems can be reduced in size only when they are unmounted, so you will be asked if the filesystem may be unmounted during the resize operation. Click Yes.

Whenever the system is booted normally, the root ( / ) and /var filesystems will be in use, so you will not be able to unmount them, and therefore the resize will fail. You'll need to use a special procedure (detailed shortly) to shrink those filesystems.

The /home filesystem is a different story; if you log in as root instead of using a normal user account, the /home filesystem will not be in use, and you can successfully shrink /home . If any non- root users have logged in since the system was booted, they may have left processes running, such as the esound daemon (esd). These can be terminated with the fuser command:

# fuser -k /home/*
/home/chris: 13464c

The output shows that the directory /home/chris was in use as the current directory ( c ) of process 13464 . That process is killed, as specified by the -k option. Once this has been done, you can resize the /home directory.

6.1.1.2.1. Creating a new logical volume

You can create a new logical volume at any time, as long as there is some free space in the volume group you wish to use.

Select the volume group's Logical View element in the lefthand panel, then click Create New Logical Volume at the bottom of the center panel. The dialog shown in Figure 6-4 will appear.

Figure 6-4. Create New Logical Volume dialog

Enter an LV name consisting of letters, digits, and underscores. Change the LV size unit from Extents to Gigabytes (or Megabytes) and enter the desired LV size directly or by using the slider (click the 'Use remaining' button to use all of the free space in the PV).

To create a filesystem in this LV, change the Filesystem type control (near the bottom of the dialog) from