Digimer at 16:23, 19 May 2010

2010-05-19T16:23:54Z

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	'''Note''': This is a snippet from another doc and still needs to be cleaned up. Please follow this with caution. It starts after a modification to a Xen domU machine.		'''Note''': This is a snippet from another doc and still needs to be cleaned up. Please follow this with caution. It starts after a modification to a Xen domU machine called 'dev01'.

	= Adding New Disk in domU to it's PV =		= Adding New Disk in domU to it's PV =

Digimer: Created page with '{{howto_header}} '''Note''': This is a snippet from another doc and still needs to be cleaned up. Please follow this with caution. It starts after a modification to a Xen domU m…'

2010-05-19T16:23:06Z

Created page with '{{howto_header}} '''Note''': This is a snippet from another doc and still needs to be cleaned up. Please follow this with caution. It starts after a modification to a Xen domU m…'

Páàjì titun

{{howto_header}}

'''Note''': This is a snippet from another doc and still needs to be cleaned up. Please follow this with caution. It starts after a modification to a Xen domU machine.

= Adding New Disk in domU to it's PV =

Once dom0's LV has been added to domU, you will need to make it available to the domU OS. In this case, we will add it to domU's existing PV.

Log into the VM; We will use [[dev01]] and it's new '''/dev/xvdb''' disk for our example.

== Preparing the Partition ==

Use '''fdisk -l''' and make sure you now see:

<source lang="text">
Disk /dev/xvdb: 53.6 GB, 53687091200 bytes
255 heads, 63 sectors/track, 6527 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/xvdb doesn't contain a valid partition table
</source>

Enter the following:

<source lang="bash">
fdisk /dev/xvdb
</source>

In '''fdisk''', enter the following:

<source lang="text">
n # New partition
p # Primary partition
1 # Partition number
<enter> # First free block
<enter> # Last free block
t # Change the new partiton's label
8e # To 'Linux LVM'
p # Print how the new partition will look and confirm that it is right
w # Write the changes to disk and exit.
</source>

This should look like:

<source lang="text">
# fdisk /dev/xvdb
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.

The number of cylinders for this disk is set to 6527.
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)
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-6527, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-6527, default 6527):
Using default value 6527

Command (m for help): t
Selected partition 1
Hex code (type L to list codes): 8e
Changed system type of partition 1 to 8e (Linux LVM)

Command (m for help): p

Disk /dev/xvdb: 53.6 GB, 53687091200 bytes
255 heads, 63 sectors/track, 6527 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/xvdb1 1 6527 52428096 8e Linux LVM

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.
</source>

== Creating the new PV ==

We need to turn the new partition into a Physical Volume so that we can then add it to the existing Volume Group. Do this by typing:

<source lang="bash">
pvcreate dev01_snap /dev/xvdb1
</source>

Wait a few seconds for background steps to complete and then check that it is now visible by LVM as a PV by typing:

<source lang="bash">
pvdisplay
</source>

If it worked, you should now see this as the output:

<source lang="text">
--- Physical volume ---
PV Name /dev/xvda2
VG Name dev01_vg1
PV Size 244.04 GB / not usable 5.90 MB
Allocatable yes (but full)
PE Size (KByte) 32768
Total PE 7809
Free PE 0
Allocated PE 7809
PV UUID 2bm15Z-vRGI-yKvp-NvGy-w1eC-mnrM-XE0GQe

"/dev/xvdb1" is a new physical volume of "50.00 GB"
--- NEW Physical volume ---
PV Name /dev/xvdb1
VG Name
PV Size 50.00 GB
Allocatable NO
PE Size (KByte) 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID kJaG6L-R31a-NTRZ-NXT4-1ldP-Egnd-0Z4f1E
</source>

== Adding the new PV to the Existing VG ==

Now that we have the second PV, we need to add it to the existing VG. We will continue with this example using the [[dev01]] VM.

To sort out what PV you want to add to which VG, run the following two commands (output shown):

<source lang="bash">pvscan</source>
<source lang="text">
PV /dev/xvda2 VG dev01_vg1 lvm2 [244.03 GB / 0 free]
PV /dev/xvdb1 lvm2 [50.00 GB]
Total: 2 [294.03 GB] / in use: 1 [244.03 GB] / in no VG: 1 [50.00 GB]
</source>

Above, we see the new PV, '''/dev/xvdb1''' is not yet assigned to a VG so we know it's the one we want and that it is ready.

<source lang="bash">vgscan</source>
<source lang="text">
Reading all physical volumes. This may take a while...
Found volume group "dev01_vg1" using metadata type lvm2
</source>

Above, we see that the existing VG is '''dev01_vg1'''. This is the VG that the new PV will be added to.

So then, run:
<source lang="bash">
vgextend dev01_vg1 /dev/xvdb1
</source>
<source lang="text">
Volume group "dev01_vg1" successfully extended
</source>

If you see the above output, then it looks like it worked. Rerun '''pvscan''' and it should now look like:

<source lang="bash">pvscan</source>
<source lang="text">
PV /dev/xvda2 VG dev01_vg1 lvm2 [244.03 GB / 0 free]
PV /dev/xvdb1 VG dev01_vg1 lvm2 [49.97 GB / 49.97 GB free]
Total: 2 [294.00 GB] / in use: 2 [294.00 GB] / in no VG: 0 [0 ]
</source>

We can see that both PVs are in the same VG.

Now create the mount point that the new snapshot partition will be mounted:
<source lang="bash">
mkdir /mnt/snapshot
</source>

{{footer}}

Adding Space to an LVM - Revision history

Digimer at 16:23, 19 May 2010

Digimer: Created page with '{{howto_header}} '''Note''': This is a snippet from another doc and still needs to be cleaned up. Please follow this with caution. It starts after a modification to a Xen domU m…'