RE [Xen-users] Resizing partitions on a VM sitting on a LVM volume

[Alain BARTHE <alain.barthe@xxxxxxxx>]

xen-users-bounces@xxxxxxxxxxxxxxxxxxx a écrit sur
10/01/2008 01:09:18 :

> Greetings all!
> 
> I emailed a little while ago about an issue similar to this one but
am 
> having issues with it....
> 
> I have a Xen VM sitting on an LVM volume.  I want to grow a file
system 
> in the VM.  So I 'lvextend' the LVM volume first from 24GB to
64.4GB. 
> No problems there.  Then I boot the VM and run parted:

We don't boot the VM at this time. We continue resizing
the partitions from the dom0. If you are resizing the VM root filesystem,
you will need to use this way.

> 
> sh-3.1# parted /dev/xvda
> GNU Parted 1.8.1
> Using /dev/xvda
> Welcome to GNU Parted! Type 'help' to view a list of commands.
> (parted) print
> 
> Model: Xen Virtual Block Device
> Disk /dev/xvda: 64.4GB
> Sector size (logical/physical): 512B/512B
> Partition Table: msdos
> 
> Number  Start   End     Size    Type
     File system  Flags
>   1      32.3kB  107MB   107MB  
primary   ext3         boot
>   2      107MB   10.6GB  10.5GB  primary
  ext3
>   3      10.6GB  19.0GB  8390MB  primary
  linux-swap
>   4      19.0GB  24.0GB  5017MB  extended
>   5      19.0GB  24.0GB  5017MB  logical
  ext3
> 
> (parted) resize 4 19.0GB 64.4GB
> (parted) resize 5 19.0GB 64.4GB
> Error: File system has an incompatible feature enabled.
> 
> So I can resize partition 4 with no problems, but can't resize partition
> 5 because of that error.  It clearly sees that the 'disk' has
more space 
> now.  Anyone know why I can't resize the filesystem/partition
this way?

I don't know why, but I experienced the same problem
with parted, so we use fdisk. You have to delete partition 4 and 5 in your
case, then recreate them with the right size.

> 
> I tried deleting the whole partition and re-creating it with the bigger
> size, then re-creating the ext3 file system in it, and that works.
 But 
> when I do that I lose all my data obviously, so I'd like to be able
to 
> just use the 'resize' command in parted....

Don't recreate your file system !!! Resize it instead.
From the dom0, run kpartx on your LV:

kpartx -a /dev/myvg/mylv

This will create entries in dev/mapper that correspond
to your partitions on the LV, something like:
/dev/mapper/myvg-mylvp1, /dev/mapper/myvg-mylvp2,
etc.

Then resize the file system on the growed partition,
something like:

resize2fs /dev/mapper/myvg-mylvp5

We used several times this method, it works. If you
want to minimize the time your domU is off, you can perform all steps except
the last one (filesystem resize) while the domU is alive.

Hope this help.

Alain.

> 
> Any advice would be greatly appreciated!!
> 
> -erich
> 
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