Resizing a lvm partition is straight forward if it doesn’t contain a partition table. Simply do a:
lvresize -L disksize /dev/vg/lv resize2fs /dev/vg/lv
If it is running a virtual machine like xen with a partition table, how to resize the domU, whether to shutdown domU or not depends largely on the partiton structure. In centos, if you do a default install, the default installation uses lvm without doing any proper partitioning, as in unlike traditional partitioning, there is no home, usr, tmp partions..etc. In a virtualised environment and with the default partitioning scheme, if you want to resize the home partition, you have to resize the root (/) partition. It is not easy to do it in domU so the best way is to do it is from domO.
Resizing domU from dom0 is more involved. So do yourself a favour by having a proper partition scheme like:
/boot / /usr /var /tmp swap space which is 2 times your ram
Having partitioning scheme like this means that you don’t need to touch / when resizing ‘/home’ or ‘/usr’ which is quite common.
Ok, its time to do the dirty job. This article is to show how to resize domU from dom0 in case you need to do it. Shutdown my domU first.
[root@bpehhome2 mapper]# xm shutdown web
This is a quick overview of my web domU.
[root@bpehhome2 mapper]# fdisk -l /dev/xenvg/XenWeb
Disk /dev/xenvg/XenWeb: 10.5 GB, 10502537216 bytes
255 heads, 63 sectors/track, 1276 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/xenvg/XenWeb1 * 1 13 104391 83 Linux
/dev/xenvg/XenWeb2 47 1276 9879975 83 Linux
/dev/xenvg/XenWeb3 14 46 265072+ 82 Linux swap / Solaris
If you try to resizefs /dev/xenvg/XenWeb straight away, resize2fs doesn’t like the MBR and will throw out error like so:
resize2fs: Bad magic number in super-block while trying to open /dev/xenvg/XenWeb Couldn't find valid filesystem superblock.
To overcome that, we need to split the partition up and resizefs them separately. Let us go through the steps in detail.
1) In domO, check that you have enough disk space. In this example, I have about 3G more. I will add 1G to the xenweb logical volume
[root@bpehhome2 mapper]# vgdisplay --- Volume group --- VG Name xenvg System ID Format lvm2 Metadata Areas 1 Metadata Sequence No 90 VG Access read/write VG Status resizable MAX LV 0 Cur LV 7 Open LV 3 Max PV 0 Cur PV 1 Act PV 1 VG Size 37.16 GB PE Size 32.00 MB Total PE 1189 Alloc PE / Size 1066 / 33.31 GB Free PE / Size 123 / 3.84 GB VG UUID 3vcgz5-1O2N-Oj89-o7KK-Tl51-wZbT-z32pgQ
2. I checked my current logical volume and resize xenweb to 1000M.
[root@bpehhome2 mapper]# lvscan ACTIVE '/dev/xenvg/root' [4.50 GB] inherit ACTIVE '/dev/xenvg/XenAuth' [8.00 GB] inherit ACTIVE '/dev/xenvg/XenDebianDefault' [2.00 GB] inherit ACTIVE '/dev/xenvg/swap' [1.00 GB] inherit ACTIVE '/dev/xenvg/XenCentOSInstall' [3.00 GB] inherit ACTIVE '/dev/xenvg/XenWeb1' [5.03 GB] inherit ACTIVE '/dev/xenvg/XenWeb' [9.78 GB] inherit [root@bpehhome2 ~]# lvresize -L 10000M /dev/xenvg/XenWeb Rounding up size to full physical extent 9.78 GB Extending logical volume XenWeb to 9.78 GB Logical volume XenWeb successfully resized
3. Now I resize the partition in XenWeb2 in /dev/xenvg/XenWeb
[root@bpehhome2 mapper]# fdisk /dev/xenvg/XenWeb
The number of cylinders for this disk is set to 1276.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
(e.g., DOS FDISK, OS/2 FDISK)
Command (m for help): p
Disk xenvg-XenWeb: 10.5 GB, 10502537216 bytes
255 heads, 63 sectors/track, 1276 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
xenvg-XenWeb1 * 1 13 104391 83 Linux
xenvg-XenWeb2 47 1150 8867880 83 Linux
xenvg-XenWeb3 14 46 265072+ 82 Linux swap / Solaris
Partition table entries are not in disk order
Command (m for help): d
Partition number (1-4): 2
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 2
First cylinder (47-1276, default 47):
Using default value 47
Last cylinder or +size or +sizeM or +sizeK (47-1276, default 1276):
Using default value 1276
Command (m for help): p
Disk xenvg-XenWeb: 10.5 GB, 10502537216 bytes
255 heads, 63 sectors/track, 1276 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
xenvg-XenWeb1 * 1 13 104391 83 Linux
xenvg-XenWeb2 47 1276 9879975 83 Linux
xenvg-XenWeb3 14 46 265072+ 82 Linux swap / Solaris
Partition table entries are not in disk order
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
WARNING: Re-reading the partition table failed with error 22: Invalid argument.
The kernel still uses the old table.
The new table will be used at the next reboot.
Syncing disks.
4. Now, its time to split the partition up. The partitions can be viewed in /dev/mapper. I want to resize2fs partition 2 only.
[root@bpehhome2 mapper]# kpartx -a /dev/xenvg/XenWeb [root@bpehhome2 ~]# cd /dev/mapper [root@bpehhome2 mapper]# ls control xenvg-XenAuth xenvg-XenWeb xenvg-XenWebp2 XenWeb2 xenvg-root xenvg-XenCentOSInstall xenvg-XenWeb1 xenvg-XenWebp3 XenWeb3 xenvg-swap xenvg-XenDebianDefault xenvg-XenWebp1 XenWeb1 [root@bpehhome2 mapper]# resize2fs XenWeb2 resize2fs 1.39 (29-May-2006) Please run 'e2fsck -f XenWeb2' first. [root@bpehhome2 mapper]# e2fsck -f XenWeb2 e2fsck 1.39 (29-May-2006) 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 /: ***** FILE SYSTEM WAS MODIFIED ***** /: 246443/2143360 files (1.0% non-contiguous), 1037188/2216970 blocks
5. Do some cleaning up.
[root@bpehhome2 mapper]# kpartx -d /dev/xenvg/XenWeb
6. boot up domU and check if everything is working
[root@bpehhome2 mapper]# xm create /etc/xen/web.cfg
I will blog about shrinking lvm with partition next which is slightly more complex.
Decent thoughts. I like your web design also. Keep up the good work.
I very much like your blog. Great content. Please continue posting such good cotent.
Err, why should you have run that on:
xenvg-XenWebp2 ?
Group : xenvg
LV : XenWeb
Partition: 2 (p2)