In this article, and in this article, we showed how to install and extend logical volumes with LVM. Now, we want to shrink the filesystem we created and the logical volume, so we can remove the drive. [Note: Before you do anything involving your partitions or volumes, make a complete backup. Make sure to set up a test system with the same kernel and distribution to see how this stuff works. This article was written using our lab box. Read our terms of use. Note that this article was written using a Fedora RC 1 distribution and a generic 2.4.24 kernel.] As we do all of this, we have a text file on our logical volume called ruk.txt that we can use to somewhat test the integrity of our filesystem and volume:
[root@srv-1 root]# mount /dev/sda1 on / type ext3 (rw) none on /proc type proc (rw) none on /dev/pts type devpts (rw,gid=5,mode=620) /dev/sdb1 on /opt type ext3 (rw) /dev/sdc1 on /usr/src type ext3 (rw) /dev/sdd1 on /usr/local type ext3 (rw) /dev/volgroup/logicalvol on /mnt type ext3 (rw) [root@srv-1 root]# cat /mnt/ruk.txt test [root@srv-1 root]# umount /mnt |
OK. We have data on our volume. Now, we want to shrink down the filesystem on our volume so we can remove one of the drives:
[root@srv-1 root]# lvmdiskscan lvmdiskscan -- reading all disks / partitions (this may take a while...) lvmdiskscan -- /dev/sda1 [ 3.75 GB] Primary LINUX native partition [0x83] lvmdiskscan -- /dev/sda2 [ 250.98 MB] Primary LINUX swap partition [0x82] lvmdiskscan -- /dev/sdb1 [ 4 GB] Primary LINUX native partition [0x83] lvmdiskscan -- /dev/sdc1 [ 4 GB] Primary LINUX native partition [0x83] lvmdiskscan -- /dev/sdd1 [ 4 GB] Primary LINUX native partition [0x83] lvmdiskscan -- /dev/sde [ 4 GB] USED LVM whole disk lvmdiskscan -- /dev/sdf [ 4 GB] USED LVM whole disk lvmdiskscan -- /dev/sdg [ 4 GB] USED LVM whole disk lvmdiskscan -- /dev/sdh [ 4 GB] free whole disk lvmdiskscan -- 8 disks lvmdiskscan -- 4 whole disks lvmdiskscan -- 0 loop devices lvmdiskscan -- 0 multiple devices lvmdiskscan -- 0 network block devices lvmdiskscan -- 5 partitions lvmdiskscan -- 0 LVM physical volume partitions [root@srv-1 root]# ot@srv-1 root]# e2fsck -f /dev/volgroup/logicalvol e2fsck 1.34 (25-Jul-2003) 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/volgroup/logicalvol: 12/1441792 files (0.0% non-contiguous), 53460/2883584 blocks [root@srv-1 root]# ot@srv-1 root]# resize2fs /dev/volgroup/logicalvol 40000 resize2fs 1.34 (25-Jul-2003) Resizing the filesystem on /dev/volgroup/logicalvol to 40000 (4k) blocks. The filesystem on /dev/volgroup/logicalvol is now 40000 blocks long. [root@srv-1 root]# |
Check our test file:
[root@srv-1 root]# mount /dev/volgroup/logicalvol /mnt [root@srv-1 root]# df Filesystem 1K-blocks Used Available Use% Mounted on /dev/sda1 3874108 1611852 2065460 44% / none 3874108 1611852 2065460 44% /dev/pts /dev/sdb1 4127076 235028 3682404 6% /opt /dev/sdc1 4127076 278956 3638476 8% /usr/src /dev/sdd1 4127076 32828 3884604 1% /usr/local /dev/volgroup/logicalvol 155872 32832 116640 22% /mnt [root@srv-1 root]# [root@srv-1 root]# ls /mnt lost+found ruk.txt [root@srv-1 root]# cat /mnt/ruk.txt test [root@srv-1 root]# [root@srv-1 root]# umount /mnt umount: /mnt: not mounted |
Our test file is still complete after resizing the filesystem. Note that the logical volume is still the same size. Let’s shrink it by 8 Gigs:
[root@srv-1 root]# lvreduce -L -8G /dev/volgroup/logicalvol lvreduce -- WARNING: reducing active logical volume to 3 GB lvreduce -- THIS MAY DESTROY YOUR DATA (filesystem etc.) lvreduce -- do you really want to reduce "/dev/volgroup/logicalvol"? [y/n]: y lvreduce -- doing automatic backup of volume group "volgroup" lvreduce -- logical volume "/dev/volgroup/logicalvol" successfully reduced [root@srv-1 root]# mount /dev/volgroup/logicalvol /mnt [root@srv-1 root]# ls /mnt lost+found ruk.txt [root@srv-1 root]# df Filesystem 1K-blocks Used Available Use% Mounted on /dev/sda1 3874108 1611996 2065316 44% / none 3874108 1611996 2065316 44% /dev/pts /dev/sdb1 4127076 235028 3682404 6% /opt /dev/sdc1 4127076 278956 3638476 8% /usr/src /dev/sdd1 4127076 32828 3884604 1% /usr/local /dev/volgroup/logicalvol 155872 32832 116640 22% /mnt [root@srv-1 root]# ot@srv-1 root]# cat /mnt/ruk.txt test [root@srv-1 root]# |
Our file is still there, and the logical volume is shrunk down. Let’s remove /dev/sdg from the volume group:
[root@srv-1 root]# vgreduce volgroup /dev/sdg vgreduce -- doing automatic backup of volume group "volgroup" vgreduce -- volume group "volgroup" successfully reduced by physical volume: vgreduce -- /dev/sdg [root@srv-1 root]# |
Let’s do a scan:
[root@srv-1 root]# pvscan pvscan -- reading all physical volumes (this may take a while...) pvscan -- ACTIVE PV "/dev/sde" of VG "volgroup" [3.99 GB / 1016 MB free] pvscan -- ACTIVE PV "/dev/sdf" of VG "volgroup" [3.99 GB / 3.99 GB free] pvscan -- inactive PV "/dev/sdg" is in no VG [4 GB] pvscan -- total: 3 [12 GB] / in use: 2 [8 GB] / in no VG: 1 [4 GB] [root@srv-1 root]# |
We are now ready to replace or reconfigure our logical volume.
There are six articles in this series:
Setting Up Logical Volume Manager
Extending a Logical Volume
Shrinking a Logical Volume With LVM
Adding a RAID1 Device to a Volume With LVM
Upgrading LVM To Version 2 and Patching The Linux Kernel
Finish Conversion And Expansion to Two RAID1 Devices With LVM
