To remove a logical volume, unmount it, and then use lvremove :
# umount /usr/lib/survey-snap
# lvremove /dev/main/survey-snap
Do you really want to remove active logical volume "survey-snap"? [y/n]: y
Logical volume "survey-snap" successfully removed
Removing an LV is irreversible, so be sure that you're not deleting any important data.
6.1.1.3.8. Adding a partition
To set up a partition for use as a physical volume, use the pvcreate command to write the LVM disk label, making the partition into a physical volume:
# pvcreate /dev/sde1
Physical volume "/dev/sde1" successfully created
If the disk is not partitioned, you can use fdisk or (more easily) parted to create a partition before running pvcreate.
These commands create a single partition that fills the entire disk /dev/sde:
# parted /dev/sde mklabel msdos# parted -- /dev/sdemkpart primary ext2 1 -1
In this case, the partition will be /dev/sde1.
You can then add that PV to an existing volume group:
# vgextend main /dev/sde1
Volume group "main" successfully extended
6.1.1.3.9. Removing a partition
The vgreduce command is used to reduce the size of a volume group by removing a physical volume. It will fail if any space on the PV is in use:
# vgreduce main /dev/sdb1
Physical volume "/dev/sdb1" still in use
In this case, an attempt to remove /dev/sdb1 from the volume group main failed. To move the data off a PV (assuming that there is sufficient space available on other PVs in the volume group), use the pvmove command:
# pvmove /dev/sde1 /dev/sde1: Moved: 100.0%
Depending on the amount of date to be moved, this operation can take quite a while to run. When it is complete, you can remove the physical volume:
# vgreduce main /dev/sdb1
Removed "/dev/sdb1" from volume group "test"
You can then use that partition for other uses. If you want to erase the LVM disk label, use the pvremove command:
# pvremove /dev/sde1
Labels on physical volume "/dev/sde1" successfully wiped
6.1.1.4. Managing LVM in single-user mode
Some filesystems, such as those containing /var or /etc , may be in use anytime the system is booted normally. This prevents the use of resize2fs to shrink ext2 and ext3 filesystems or to grow them large enough to exceed the block group descriptor table.
To use resize2fs on these filesystems, you must use runlevel s , which is single-user mode. Boot your system, and press the spacebar when the GRUB boot screen appears. Press the A key to append text to the boot line; then type s and press Enter. After a few seconds, a root shell prompt will appear ( sh-3.1# ).
At this shell prompt you can unmount the filesystem, then use fsck , resize2fs , and lvreduce (or lvextend ). For example, to reduce the size of /home to 925 MB:
sh-3.1# umount /home
sh-3.1# fsck -f /dev/main/home
e2fsck 1.38 (30-Jun-2005)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/main/home: 121/256000 files (2.5% non-contiguous), 12704/262144 blocks
sh-3.1# resize2fs /dev/main/home 900M
resize2fs 1.38 (30-Jun-2005)
Resizing the filesystem on /dev/main/home to 230400 (4k) blocks.
The filesystem on /dev/main/home is now 229376 blocks long.
sh-3.1# lvreduce /dev/main/home --size 950 M
Rounding up size to full physical extent 952.00 MB
WARNING: Reducing active logical volume to 952.00 MB
THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce home? [y/n]: y
Reducing logical volume home to 952.00 MB
Logical volume home successfully resized
sh-3.1# resize2fs /dev/main/home
resize2fs 1.38 (30-Jun-2005)
Resizing the filesystem on /dev/main/home to 243712 (4k) blocks.
The filesystem on /dev/main/home is now 243712 blocks long.
The warning message displayed by lvreduce is accurate: if you set the logical volume size smaller than the filesystem size, you will lose data! Be extremely careful when resizing volumes; it's a good idea to back up your data first.
If your system has the default Volume Group and Logical Volume names, substitute the correct name (such as /dev/VolGroup00/LogVol00) for /dev/main/home. The problem is that it's hard to keep the logical volume names straightwhich is why I recommend using more meaningful names.
Note that, as before, the filesystem was resized to be slightly smaller than the desired size, then expanded to fill the LV after the LV was resized.
When you're done, type reboot or press Ctrl-Alt-Delete to restart the system.
6.1.1.5. Managing LVM in rescue mode
To reduce or substantially grow the root filesystem, you'll have to boot from a device other than your normal disk. The most convenient way to do this is to boot from the Fedora Core installation media; when the boot screen appears ( Figure 1-1 ), type linux rescue and press Enter.
After prompting you for the language ( Figure 1-5 ) and keyboard type ( Figure 1-6 ) the same way it does for a network installation (use the arrow keys and Enter to select the correct value for each), the system will ask if you wish to start the network interfaces, as shown in Figure 6-6 . Select No by pressing Tab and then Enter.