This page is part of my webdevster.com tutorial, see index to OpenQRM and XEN LVM based HVM VM.

[2.6] Step 6. Xen Troubleshooting and Optional Useful CLI Commands

Here are some troubleshooting examples, and some very useful CLI commands. Even though we use OpenQRM to manage the Xen Host, it’s a good idea to know these commands.

If you need to install nic drivers on new vm:

Copy the nic drivers to cdrom, than insert cdrom into Xen host cdrom drive, than run the following command on Xen VM:

After install Unmount

If VM eth0 doesn’t come up.

Their are two solutions, the first is fixing the root of the problem, Use a permanent mac address found in /etc/xen/vmx01cms01.cfg, to permanently keep the same ethX. The second, is being caused by the VM thinking there is a new NIC installed.

First Solution:

Second Solution:

Make a note of the eth device number, i.e. eth3

change:

eth0

to

eth3

You shouldn’t get this problem if you didn’t change the permanent MAC address.

If you want to mount VM’s LV.

You can view the VM’s LV partitions on Xen host with:

Disk /dev/vol/vmx01cms01: 16.1 GB, 16106127360 bytes
255 heads, 63 sectors/track, 1958 cylinders, total 31457280 sectors
Units = sectors of 1 * 512 = 512 bytes
Disk identifier: 0x0008ae25
 
               Device Boot      Start         End      Blocks   Id  System
/dev/vol/vmx01cms01p1   *          63    23438834    11719386   83  Linux
/dev/vol/vmx01cms01p2        23438835    31455269     4008217+  82  Linux swap / Solaris

Since the VM’s LV is a whole disk containing partitions, you can’t simply mount it. You first need to create maps to the individual partitions.

Make sure to umount it, when your done:

Remove device mapping

If you want to use XM console.

XM Console works in Paravirtualization with little fuss, but with HVM (full virtualization), XM Console is rather cumbersome to setup, therefore you can ssh or vnc into initial installation of the HVM VM. If you are brave to install xm console for hvm, visit, zhigang.org Xen FAQ.

Useful XEN and VM CLI commands and tips.

Here are some useful CLI commands, which OpenQRM will mostly facilitate for us with the WebUI.

Some common xen commands:

Start:

Shutdown:

Or Destroy (Unplug the VM from outlet)

View running VMs, in real mode:

List running VMs:

If you want to delete VM and the LVs

If you want to delete all VM and LV, and start from scratch

For reference only. Might not work for LVs inside an LV.

Unplug the VM

Unmount LV (probably not mounted anyway’s, for reference only)

Deactivate it

Delete LV

Nothing to display.

Now simply delete the vmx01cms01.cfg, VM file.

You now have no VM and no LV.

Don’t forget to change the fstab, in case you mounted any of these LVs.

Don’t forget to empty out your ssh known host, if your using the same LV configs again.

If you want to resize LV (Shrinking)

For reference only. Might not work for LVs inside an LV.

Unmount (just in case it’s mounted) so we can shrink

Resize VG

Resize LV

Show Results

Remount - Optional

Some Useful CLI commands and GUI, for LV

LVM Managing - CLI

LVM Managing - GUI

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