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When you create a VM Citrix Xen Cloud Platform (using a storage on Network or on local server) you assign a specific amount of space i.e. 20 GB or 30GB but after sometime client ask for more disk space you have to reboot the server to attach or add more disk space. In this post I will explain how you can add additional disk space to a Linux Xen VM without downtime.

Note: This method work if you have created Logical Volumes at the time of OS setup.

ADD ADDITIONAL DISK SPACE

1) Login to Xen Center and search the VM in which you want to extend the space.

2) Click on VM to open its section and go to Storage tab. You will see something like below image

Here you will see the position, name, description, size etc. of existing Disk (Virtual Disk).

3) Now click on “Add” which will show following window (Popup)

Here, Enter the Name, description and size of Disk you want to attach. Then select the location (list all the storage volumes added in the cloud or server) on which you want to create the disk. Press Add.

4) On VM properties (under storage tab) you will able to see the newly added disk.

CONFIGURE AND EXTEND DISK SPACE

1) Login to the server through SSH (Root User) and check Current disk space using command “df -h”

2) Execute command “fdisk -l” which will show all the current partitions on all the disks.

It will show “Disk /dev/xvdb doesn’t contain a valid partition table” which mean the server has detected the additional disk.

3) Now initialize the PhysicalVolume using command “pvcreate”

4) Add the above initialized PhysicalVolume to existing group with “vgextend”

5) Increase the size of existing Logical Volume using command “lvextend“.

6) Final step, without this step Linux will not detect the extended partition or space. Use command ” “resize2fs“ which will resize the file system and update kernel with extended space of logical volume.

Now check the disk space using “df -h” and you will able to see the increased disk space

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You have installed Citrix Xen Cloud Platform (XCP) and configured it (including network, templates, OS ISO’s etc.; even you have created your first VM with the help of documentation provided by Citrix but when you try to boot your VM for first time it throws following error as Citrix is not able to boot the VM from CD/DVD drives which are attached to it.

The problem here is the boot order for the VM is not properly set (through Template) at the time of VM creation and VM remains Halted

To fix this error first we need to check the boot sequence for the VM. Use following command to check it

The above output shows that boot order is not set (“HVM-boot-params (MRW)” is blank) for the VM. Now, execute following command to set boot sequence of the VM

Verify the boot order now.

We can see that boot order (HVM-boot-params (MRW)) is set to “dc” i.e. CD/DVD

Thats it!!! You should able to start the VM and boot it from ISO you have mounted.

NOTE: In this post “5ce47d4e-227c-9d1e-4710-21b7c998318e” is the UID of the VM and it will different in your case. So, make sure to change the UID before executing the commands.