Re: [Xen-users] increase size for dom guest using lvm online

[Simon Hobson <linux@xxxxxxxxxxxxxxxx>]

I wrote:

> It may be possible to detatch a volume and re-attach it with xm but 
> I've never done that.
Well now I have. Advance planning says I'll need a bit more space on 
a volume, and there was a little bit of space available on the iSCSI 
box (so a case of grab it while it's there, before someone else does 
!).
Unmounted the volume in the guest, then :

# cat backup
<stuff deleted>
disk    = [ 'phy:vg0/backuproot,xvda1,w', 
'phy:vg0/backupvar,xvda2,w', 
'phy:/dev/disk/by-path/ip-<very-long-iscsi-address>,xvda3,w', 
'phy:vg0/backupswap,xvda4,w' ]
# xm list
Name                                        ID   Mem VCPUs      State   Time(s)
Domain-0                                     0   486     4     r-----  67982.4
backup                                      11   511     2     -b---- 135441.2

# xm block-detach 11 xvda3

<do any other steps required, such as altering partitions or resizing 
LVM volumes>
# xm block-attach 11 '/dev/disk/by-path/ip-<very-long-iscsi-address>' 
/dev/xvda3 r
Error: Device 51715 (vbd) could not be connected. Hotplug scripts not working.
Usage: xm block-attach <Domain> <BackDev> <FrontDev> <Mode> [BackDomain]

Create a new virtual block device.

Checked in teh guest and the device didn't re-appear, so tried again :

# xm block-attach 11 '/dev/disk/by-path/ip-<very-long-iscsi-address>' 
/dev/xvda3 r
Error: Device /dev/xvda3 (51715, vbd) is already connected.
Usage: xm block-attach <Domain> <BackDev> <FrontDev> <Mode> [BackDomain]

Create a new virtual block device.


So I still had to shutdown and re-create the guest for the size 
change to appear.


> In any case, at least with ext3, you need the filesystem unmounted 
> in order to resize it.
As "Bart Van Kerckhove" <bart@xxxxxxxx> pointed out, you can do 
online resize of an ext3 filesystem :
# df -h /store
Filesystem            Size  Used Avail Use% Mounted on
/dev/xvda3             99G   44G   51G  47% /store

# resize2fs /dev/xvda3
resize2fs 1.41.3 (12-Oct-2008)
Filesystem at /dev/xvda3 is mounted on /store; on-line resizing required
old desc_blocks = 7, new_desc_blocks = 10
Performing an on-line resize of /dev/xvda3 to 39321087 (4k) blocks.
The filesystem on /dev/xvda3 is now 39321087 blocks long.

# df -h /store
Filesystem            Size  Used Avail Use% Mounted on
/dev/xvda3            148G   44G   97G  31% /store
--
Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.

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