Crucial Paradigm

You can use the following commands to change the Citrix XenServer pool’s master server:

First you need to disable high availibility:

xe pool-ha-disable

Then you need to find out which host you want to change the master to:

xe host-list

Then change the master:

xe pool-designate-new-master host-uuid=[uuid of new master host]

Turn HA back on:

xe pool-ha-enable

Sometimes when shutting down a VM via the standard XenCenter interface or command line (xe) on a Citrix XenServer machine the shutdown will not complete.  The first thing to try is a force shutdown on the VM:

xe vm-shutdown –force vm=[vm name]

If this still doesn’t work you can try taking a look in the XenServer pending task queue:

xe task-list

And cancel the process’ that seem to be holding up the system:

xe task-cancel uuid=[task uuid]

If this still fails you can try the following:

xe-toolstack-restart

If you have noticed your Citrix XenServer machine grind to a halt due a process “cdrommon” this is a known bug with a particular CD-ROM drive in XenServer.  A fix for the bug can be found here:

http://support.citrix.com/article/CTX126919

In short to check if you are effected by the bug, run the following:

dmesg | grep DV-28

This bug applies to “TEAC DV-28E-V” CD-ROm drives.

Adding a local storage repository to a Citrix XenServer 5.x server can be done as follows:

NOTE: Extra precaution should be taken while using the following commands, as it could result in data loss.  Only perform these steps if you know what you are doing:

1. Locate the disk ID by using the following command:
   # ls -al /dev/disk/by-id
2. Create the local storage repository:
   # xe sr-create content-type=user device-config:device=/dev/disk/by-id/<scsi-xxxxxxxxxxxxxxxxxxxxxxxxx> name-label=”Local Storage X” shared=false type=lvm

If you ever wondered how to remove the physical NIC configuration on a Citrix XenServer machine, this is how you can do it:

xe pif-reconfigure-ip uuid=XXXXXXXXXXX mode=none

Where “XXXXXXXXXXX” is the uuid of the NIC to remove the configuration from, this can be either a NIC or a bond.  To find out the NIC/bond uuid you can run the following command:

xe pif-list

If you have tried installing any software on XenServer you will know that it is not an easy process. This article shows how you can install smartctl on a XenServer server. Smartctl is a great utility to monitor drives and if they have had any errors.

To install run the following:

wget ftp://ftp.pbone.net/mirror/archive.fedoraproject.org/fedora/linux/releases/8/Everything/i386/os/Packages/smartmontools-5.37-7.fc8.i386.rpm
wget ftp://ftp.pbone.net/mirror/archive.fedoraproject.org/fedora/linux/releases/8/Fedora/i386/os/Packages/mailx-8.1.1-46.fc7.i386.rpm
rpm -hiv smartmontools-5.37-7.fc8.i386.rpm mailx-8.1.1-46.fc7.i386.rpm

You now have smartctl installed on XenServer!

If the physical interface used for the manage interface needs to be changed, edit the MANAGEMENT_INTERFACE field /etc/xensource-inventory file on the host to reflect the new interface being used. Make sure you use the bridge interface (e.g. xenbr0) and not the physical NIC.

Once you have made this modification you will need to run the following:

xe-toolstack-restart

Rather than copying a virtual machine to the ESXi hardware node, there is a quick easy way to upload it via the VMware vSphere client.  This can be done by doing the following:

1. In the vSphere client, click on the server.
2. Click on the summary tab.
3. Right click on datastore -> Browse Datastore
4. Use the icon with the up arrow in front of some disks (Upload files to this datastore)
5. Upload the folder or files that you require.
6. Create a new (or use an existing) VM and use the vmdk file you have uploaded.

We have had a few issues lately when doing migrations from one server to another in HyperVM. It seems for some reason HyperVM just shows the VPS as being migrated and never leaves this state (for several hours). To fix this you can just run the following command on the HyperVM master:

pkill -f switchserver.php

IMPORTANT: Make sure you keep a backup of your VPS!

Xen and OpenVZ can be seen as one of the same both being virtualisation technologies they are actually very different. As a lot of you know Crucial Paradigm has been offering Xen based virtual private servers for some time now and to date we’ve built up a solid name for ourselves due to the stability and performance of the product we offer.

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