Greetings...!
This is my first blog post. Here I'm going to discuss a use case where an automated linked clone pool with persistent disk is required to move from one Virtual Center server to another one. Many of you might be familiar with the traditional process of upgrading linked clone pools using the step by step upgrade process which include one by one upgrade of View, vCenter, ESX, Parent VM and finally upgrading the pool using a recompose operation to a new snapshot created after upgrading the parent Virtual Machine. The detailed process is described in VMware View Upgrade Guide. But if someone is looking for moving linked clone pools with user data and ownership to another vCenter server then it is not easy as upgrade and there is no straight defined method to perform such migration. But leveraging some of the View features we can achieve the migration of such pools to a different vCenter Server maintaining the data and ownership.
First of all let us see how an SVI pool is internally constructed. An 'Automated Linked Clone Pool' internally refers to a 'Deployment Group'. The pool specification will be according to attributes defined in the Deployment Group and it comprises of information regarding the Virtual Center, Parent VM and Snapshot information of the linked clone pool. The vCenter information will be tagged with its vCenter ID. As an Admin, one can edit an SVI pool and change certain Pool Settings, Provisioning and vCenter Settings. But the vCenter for a pool cannot be changed at any instance. Becacues any change to the vCenter information will cause losing the structre of Deployment Group and View Connection Server and Composer will lose track of the vCenter objects for the pool. Hence for a given pool it is not possible to edit vCenter by any means of the method.
Here if admin wants to move the pool to a new set of ESX/Clusters then it can be changed in vCenter settings during pool edit wizard. A successful rebalance followed by this action will ensure that the pool is using the new ESX/Cluster resources. This is a feasible option for those want to move the pools from vCenter 4 to vCenter 4.1 without disturbing the existing 4.0 ESX Cluster. This can be done as follows
- Upgrade Virtual Center from 4.0 to 4.1
- Create a new cluster using new ESX 4.1 machines in the same vCenter Server
- From View Administrator edit the pool, and in vCenter settings select new cluster as the resource pool
- Rebalance the pool (You can also recompose the pool in case if you want to want to refer to new snapshot of a ESX 4.1 VM)
How can we migrate pool from one vCenter to another one? It will not be a pure migration as such but can be achieved by moving the persistent disks along with user ownerships. As an example here I am discussing how to perform the same from a vCenter 4.0 to 4.1. Let us assume that there are two vCenter servers available 4.0 and 4.1and ESX servers on both has access to at least one common SAN storage LUN. In this vCenter 4.0 is configured with a View 4.5 Connection Server and an SVI pool exists on this vCenter. As a first step to the migration, from the pool inventory 'delete' the pool you will get a confirmation dialogue box as below
Choose the option 'Use following datastore' and browse for the common datastore which is presented across ESX in both the vCenters. The pool should be deleted from the connection server leaving all the persistent disks on the chosen datastore. Now from the Server TAB in View administrator page add the second vCenter and configure the View composer. Add the same domain accounts in the View composer configuration which was used on the first one. Create a new automated linked clone pool on the new vCenter. Make sure that you use a snapshot of an OS that is same as the old pool. The new pool should be created with following provisioning settings
- provision desktops on demand
- minimum no of desktops = 1
- maximum number of desktop = greater than or equal to the no of VMs in the old pool
Once the pool is created entitle the pool to all users who all were entitled in old pool. Now the task is to create the desktop for each user keeping thier old data. For that open the 'Persistent disks' page and select 'Detached' tab. All the persistent disks which were archived from the old pool will be listed here.
You may notice that those entire archived persistent disks will have the "Last Pool" column blank. This is because the old pool (or the source pool for those persistent disks) was deleted. Now each persistent disks has to be edited and associated with the new pool. Depending upon the number of persistent disks this may be a tedious job because as of now there is now way of editing 'multiple selected persistent disks' from the 'View Administrator' page. So you have to edit each persistent disk and need to choose the newly created linked clone pool.
Here one thing you will notice that the user ownership for each datadisks are maintained properly. Once completing the edit task you will able to easily create linked clones in the new pool for each persisten disks. Using Control (or shift) key select all the edited persistent disks and click on the "Recreate Desktop" button
All the linked clones will be immediately provisioned and user settings and data will be intact in each VMs.
Now you will have a pool in the new vCenter which is same as that of the old pool.
