[CentOS] Existenial doubt about Xen and LVMs

Tue May 27 11:48:02 UTC 2008
Sergio Belkin <sebelk at gmail.com>

2008/5/26 Kanwar Ranbir Sandhu <m3freak at thesandhufamily.ca>:
> On Mon, 2008-05-26 at 12:38 -0300, Sergio Belkin wrote:
>> Hi,
>> I have a Dom0 with LVMs. Also, I have 2 DomU's. What happen with DomU
>> partitions if I resize Dom0 volumes? They changes of size too?
>
> So, your domUs are installed in LVs?

Thanks Ranbir,
My Dom0 looks as follows:

Disk /dev/sda: 159.8 GB, 159896305664 bytes
255 heads, 63 sectors/track, 19439 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1        1275    10241406   83  Linux
/dev/sda2            1276        1530     2048287+  82  Linux swap / Solaris
/dev/sda3            1531       19439   143854042+  8e  Linux LVM

and this lvs output:

  LV    VG   Attr   LSize   Origin Snap%  Move Log Copy%
  devel xen  -wi-a-  15.00G
  squid xen  -wi-ao 122.19G

name = "something"
uuid = "be9eb3a1-2a3b-6af4-e1a3-c2446b311ab0"
maxmem = 2000
memory = 2000
vcpus = 1
bootloader = "/usr/bin/pygrub"
on_poweroff = "destroy"
on_reboot = "restart"
on_crash = "restart"
vfb = [ "type=vnc,vncunused=1,keymap=en-us" ]
disk = [ "phy:/dev/xen/squid,xvda,w" ]
vif = [ "mac=01:16:3e:2e:f5:cb,bridge=xenbr0" ]

This the "something" data disk:

Disk /dev/xvda: 131.1 GB, 131197829120 bytes
255 heads, 63 sectors/track, 15950 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

    Device Boot      Start         End      Blocks   Id  System
/dev/xvda1   *           1        1530    12289693+  83  Linux
/dev/xvda2            1531        1785     2048287+  82  Linux swap / Solaris
/dev/xvda3            1786       15950   113780362+  83  Linux




Well, think about the domU as if
> it's a real machine: if the HD changes size, you have to change the
> partitions and LVs in order to see that change.
>
> For example, if you increase the size of the dom0 LV the domU is
> installed in, you have to:
>
> 1. increase the partition size of /dev/xvda in the domU

How do I it?

> 2. increase the PV size in the domU (unless you create a new PV on a
>   new partition created from the bigger /dev/xvda)
> 3. increase the size of the VG in the domU
> 4. add space to those LVs in the domU you want the
>   additional /dev/xvda/ space to go to.
>
> It's really easy to do the above, but you'll need to reboot your domU
> every time you change the partition table for its "HD" (i.e. /dev/xvda).
>
> HTH,
>
> Ranbir
>





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