Re: [Xen-users] how do I increase a LVM based xen domU?

["Fajar A. Nugraha" <fajar@xxxxxxxxx>]

Rudi Ahlers wrote:
>
>
>
>     If you install it using anaconda (which is what you get if you use
>     virt-manager) the default partitioning scheme is to use LVM on domU.
>     This is (1), which AFAIK is what RH recommends. It will enable
>     easy disk
>     addition (you dan do xm block-attach online without having to restart
>     domU).
>
>
> With Virt-install I can at least choose all the packages I need to
> install,

Correct.

> and the installation files are on the server already, so I don't need
> to waste bandwidth every time I install it. 
>
In my case I have a local yum mirror containing all packages I need. So
after the template-based installation I can simply do "yum install <any
additional package>" without wasting internet BW.

If you still want to use virt-install but don't want to use the default
LVM setup on domU, you might be able to use Pasi's suggestion to resize
the disk. If you choose that, it will be a LOT easier if you simply put
only one partition on each disk. Meaning you need 2 disks on domU, one
for "/" and one for swap.

>
> Would it be better to install the VPS with an ext3 partition instead
> of LVM? In which case it will have 3 partitions (/boot, / & swap) but
> that shouldn't be a problem, right?

You only need two. "/boot" doesn't need to be on separate fs. Here's an
example :

memory = "2000"
disk =    [
    'phy:/dev/VG/domUrootLV,hda1,w',
    'phy:/data/VG/domUswapLV,hda2,w',
    ]
bootloader="/usr/bin/pygrub"

I use hda1/2, but sda1/2 or xvda1/2 should work as well.
AFAIK virt-install isn't able to use LVM dom0 directly as partition on
domU though.

> Can an ext3 partition (for the domU)  on a LVM (dom0) be resized easily?
Yes. See this comparison :
- LVM dom0 -> disk on domU -> lvm domU -> ext3 on LV : add new disk to
domU (online addition possible), extend domU's VG, extend domU's LV,
resize fs.
- LVM dom0 -> disk on domU -> ext3 on partition : resize dom0's LV,
reboot domU, change domU's partition, run partprobe (or reboot domU
again), resize fs.
- LVM dom0 -> parition on domU -> ext3 on partition : resize dom0's LV,
reboot domU, resize fs on domU.

It can also be mounted on dom0 easly.

>  
>  
>
>     On dom0:
>     - create a new LV (10GB or whatever) on dom0
>     lvcreate -L 10G -n wiseguy2 System
>     - attach the block device as xvdb1 (or whatever partition currently
>     unused on domU)
>     xm block-attach server phy:/dev/System/wiseguy2 xvdb1 w
>
>
>
> Do I need to create a configuration file for the wiseguy2 domU manually?
This step doesn't require a new config file yet. But yes, ultimately you
need to create wiseguy2's config manually. You can use wiseguy's config
as a starting point. Change wiseguy -> wiseguy2 and xvda -> xvda1.

>  
>
> And then, for the following steps, for I need to mount
> /dev/System/wiseguy2 on say /mnt/wiseguy2 - on dom0, or do I need to
> boot wiseguy2 domU ?
No. The steps that I wrote is on a runnning wiseguy domU. Note the "xm
block-attach" command previously? It's used to attach new disk to a
running domU.

You can do it on dom0, but it'd be harder because it involves kpartx.
See
http://lists.xensource.com/archives/html/xen-users/2007-07/msg00777.html
for example.

Regards,

Fajar

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