How to create and remove a linux logical volume and filesystem
Gather information
In this example we would like to add a 10G filesystem to the system volume group, so we need to determine if the volume group (system) has enough free space.
Check the status of the mounted filesystems
df -h
Filesystem Size Used Avail Use% Mounted on /dev/mapper/system-root 10G 3.2G 6.9G 32% / udev 474M 184K 474M 1% /dev /dev/sda1 102M 40M 63M 39% /boot /dev/mapper/system-home_lv 2.0G 872M 1.2G 43% /home
Use the vgdisplay command to list the volume groups (VGs) and check the available space in the chosen VG.
vgdisplay
--- Volume group --- VG Name system System ID Format lvm2 Metadata Areas 1 Metadata Sequence No 16 VG Access read/write VG Status resizable MAX LV 0 Cur LV 4 Open LV 4 Max PV 0 Cur PV 1 Act PV 1 VG Size 233.66 GB PE Size 4.00 MB Total PE 59816 Alloc PE / Size 5428 / 21.20 GB Free PE / Size 54388 / 212.45 GB VG UUID efvr7g-grgf5g-V0SP-45gdf-Xber-VKzj-fg5hf
The "Free PE / Size 54388 / 212.45 GB" line shows that we have 212.45 GB free in this volume group.
Create the logical volume
To create the logical volume use the lvcreate command as follows.
lvcreate -L 10G -n optlv system
Logical volume "optlv" created
This creates a 10GB logical volume named optlv in the volume group called system.
Create a reiserfs filesystem
If you require a reiserfs filesystem then follow this step else skip to the next step to create a ext3 filesystem.
(Reiser filesystems are often used on Suse linux).
mkfs.reiserfs /dev/system/optlv
mkfs.reiserfs 3.6.19 (2003 www.namesys.com)
A pair of credits:
BigStorage (www.bigstorage.com) contributes to our general fund every month,
and has done so for quite a long time.
The Defense Advanced Research Projects Agency (DARPA, www.darpa.mil) is the
primary sponsor of Reiser4. DARPA does not endorse this project; it merely
sponsors it.
Guessing about desired format.. Kernel 2.6.16.21-0.25-smp is running.
Format 3.6 with standard journal
Count of blocks on the device: 2621440
Number of blocks consumed by mkreiserfs formatting process: 8291
Blocksize: 4096
Hash function used to sort names: "r5"
Journal Size 8193 blocks (first block 18)
Journal Max transaction length 1024
inode generation number: 0
UUID: 571e5090-af78-4732-a058-c96596d829bc
ATTENTION: YOU SHOULD REBOOT AFTER FDISK!
ALL DATA WILL BE LOST ON '/dev/system/optlv'!
Continue (y/n):y
Initializing journal - 0%....20%....40%....60%....80%....100%
Syncing..ok
ReiserFS is successfully created on /dev/system/optlv.
Create an ext3 filesystem
Use the mkfs.ext3 command to make an ext3 filesystem.
mkfs.ext3 /dev/system/optlv
mke2fs 1.38 (30-Jun-2005)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
1310720 inodes, 2621440 blocks
131072 blocks (5.00%) reserved for the super user
First data block=0
80 block groups
32768 blocks per group, 32768 fragments per group
16384 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 24 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
Mounting the filesystem
Create the directory to mount the new filesystem.
mkdir /opt
Then mount the directory onto the new mount point.
mount /dev/system/optlv /opt
Check the status of the new filesystem.
df -h
Filesystem Size Used Avail Use% Mounted on /dev/mapper/system-root 10G 3.2G 6.9G 32% / udev 474M 188K 474M 1% /dev /dev/sda1 102M 40M 63M 39% /boot /dev/mapper/system-home_lv 2.0G 872M 1.2G 43% /home /dev/mapper/system-optlv 10G 33M 10G 1% /opt
Edit /etc/fstab to ensure that the new filesystem mounted on /opt is mounted at system boot.
This example is for a reiserfs. Change reiserfs in the table below to ext3 for an ext3 filesystem.
/dev/system/root / reiserfs acl,user_xattr 1 1 /dev/sda1 /boot reiserfs acl,user_xattr 1 2 /dev/system/swap swap swap defaults 0 0 /dev/system/home_lv /home reiserfs acl,user_xattr 1 2 proc /proc proc defaults 0 0 sysfs /sys sysfs noauto 0 0 usbfs /proc/bus/usb usbfs noauto 0 0 devpts /dev/pts devpts mode=0620,gid=5 0 0 /dev/system/optlv /opt reiserfs acl,user_xattr 1 2
Removing a filesystem and logical volume
Unmount the filesystem.
umount /opt
Then remove the logical volume. Removing the logical volume will also remove the filesystem
lvremove /dev/system/optlv
Do you really want to remove active logical volume "optlv"? [y/n]: y Logical volume "optlv" successfully removed
Then edit and remove the entry from /etc/fstab.
Then remove the mount directory.
rmdir /opt