Citrix XenServer

• Missing login prompt
• Change a VM from HVM fully-emulated to PV
• Find the VNC port
• Auto start on host boot
• Backup/Restore
  • Mounting a partition on the Xen host

Missing login prompt

Debian 4.1 kernels require the boot parameter ''xencons=tty'' and ''clocksource=jiffies'' to be added via /boot/grub/menu.lst

Ubuntu 10.04 LTS needs a change to ''/etc/init/tty1.conf'' replacing tty1 with hvc0.

respawn
exec /sbin/getty -8 38400 hvc0

~# initctl reload tty1

Change a VM from HVM fully-emulated to PV

Fully emulated is crashy and slow, you want to run in xen-aware mode for optimal performance.

You must have a xen-aware kernel installed (-xen or -server) and have changed your ''/etc/fstab'' to use UUID's instead of /dev/hda?.

~# xe vm-list name-label=testVM
uuid ( RO)           : b17d71d2-d2ef-f62c-3050-5a8324bb9f5d
     name-label ( RW): testVM
    power-state ( RO): running

~# xe vbd-list vm-name-label=testVM empty=false 
uuid ( RO)             : 623f7c34-56b1-9f27-9bf3-8d6b38b58801
          vm-uuid ( RO): b17d71d2-d2ef-f62c-3050-5a8324bb9f5d
    vm-name-label ( RO): testVM
         vdi-uuid ( RO): 49cbed56-d870-4654-aef5-f8ba7ea19d52
            empty ( RO): false
           device ( RO): hda

~# xe vbd-param-list uuid=623f7c34-56b1-9f27-9bf3-8d6b38b58801 param-name=bootable
false

~# xe vbd-param-set uuid=623f7c34-56b1-9f27-9bf3-8d6b38b58801 bootable=true

~# xe vm-param-clear uuid=b17d71d2-d2ef-f62c-3050-5a8324bb9f5d param-name=HVM-boot-policy

~# xe vm-param-set uuid=b17d71d2-d2ef-f62c-3050-5a8324bb9f5d PV-bootloader=pygrub

Find the VNC port

# xenstore-ls /local/domain/$(xe vm-param-get uuid=$(xe vm-list name-label=vm02 --minimal) param-name=dom-id)/serial
 vnc-port = "5902"

The VNC port is localhost:5902

~> ssh -L5900:localhost:5902 root@xenserver

Auto start on host boot

xe vm-param-set uuid=e5dccf45-313f-e7df-d897-15c41ee3e802 other-config:auto_poweron=true

Backup/Restore

http://support.citrix.com/article/CTX121099

http://www.ervik.as/index.php/citrix-mai ... ve-virtual-machines-on-a-local-disk

• Create a filesystem backup for the XenServer host from /dev/sda1 to /dev/sda2 (XenServer's upgrade/restore partition):

[/nfs is an NFS share created on a remote NFS server]

[root@xenserver ~]# xe host-backup file-name=/nfs/xenserver-20100828
[root@xenserver ~]# xe host-restore file-name=/nfs/xenserver-20100828

• Export the metadata about the VM's to a file:

[root@xenserver ~]# xe vm-export filename=/nfs/xenserver-metadata --multiple metadata=true

• Export the metadata to 'Local Storage' (your default storage). If you were taking disks to be attached to another XenServer (think of an external disk array), the Storage already has the information about the VM's it contains:

[root@xenserver nfs]# xe-backup-metadata -h
Usage: /opt/xensource/bin/xe-backup-metadata [-h] [-i] [-u <SR UUID>]

 -h: Display this help message
 -c: Create a backup VDI if one cannot be found (default: false)
 -i: Initialize the backup VDI before performing the backup
 -u: UUID of the SR you wish to backup to
 -d: Dont perform a backup, but leave the disk mounted in a shell
 -k: Number of older backups to preserve (default: 25)
 -n: Just try to find a backup VDI and stop the script after that
 -v: Verbose output


Use the -d option to examine the backup VDI, and restore it if necessary.
It is a good idea to copy the backup onto the control domain before
restoring it via the xe pool-database-restore CLI command.

[root@xenserver nfs]# xe-backup-metadata -v -c
Using SR: Local Storage
Creating new backup VDI: f8c4577e-4db5-4ddb-a1ee-5c8c975f4f57
done
Rotating old backups: found 0
Backing up pool database: done
Cleaning old VM metadata: done
Backing up SR metadata: done
Backing up VM metadata: done
Backing up Template metadata: done

[root@xenserver nfs]# xe-backup-metadata -v
Using SR: Local Storage
Rotating old backups: found 1
Backing up pool database: done
Cleaning old VM metadata: done
Backing up SR metadata: done
Backing up VM metadata: done
Backing up Template metadata: done

• You may want to schedule metadata backups to your SR (this only protects you if your storage SR is OK and you need to restore XenServer or a specific VM's metadata).

[root@xenserver ~]# xe sr-list name-label=Local\ Storage --minimal
6b559c73-65e6-3475-e49b-78e880f869cd

[root@xenserver ~]# /opt/xensource/bin/xe-backup-metadata -v -u 6b559c73-65e6-3475-e49b-78e880f869cd
Using SR: Local Storage
Rotating old backups: found 3
Backing up pool database: done
Cleaning old VM metadata: done
Backing up SR metadata: done
Backing up VM metadata: done
Backing up Template metadata: done

[root@xenserver ~]# crontab -l
@daily /opt/xensource/bin/xe-backup-metadata -v -u 6b559c73-65e6-3475-e49b-78e880f869cd

Mounting a partition on the Xen host

Using the kpartx tool to access partitions of a virtual disk:

http://support.citrix.com/article/CTX117791

(Does not work with the new VHD format).