[CentOS-virt] Resizing disks for VMs

Mon Sep 28 16:37:10 UTC 2009
Fabian Arrotin <fabian.arrotin at arrfab.net>

Dennis J. wrote:
> Hi,
> Is there a way to make a PV xen guest aware of a size change of the host 
> disk? In my case I'm talking about a Centos 5.3 host using logical volumes 
> as storage for the guests and the guests running Centos 5.3 and LVM too.
> What I'm trying to accomplish is to resize the logical volume for the guest 
> by adding a few gigs and then make the guest see this change without 
> requiring a reboot. Is this possible maybe using some kind of bus rescan in 
> the guest?

No, it's not possible unfortunately. On a traditionnal SCSI bus you can 
rescan the whole bus to see newer/added devices or just the device to 
see newer size, but not on a Xen domU .
At least that's what i found when i blogged about that . See that thread 
on the Xen list : 

So what i do since then is to use lvm in the domU as well and add a new 
xvd block device to the domU (aka a new LV on the dom0) and then the 
traditionnal pvcreate/vgextend/lvextend. Working correctly for all my 
domU's ..

Fabian Arrotin
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