vCenter

vSphere 6.5 PSC’s – Multisite SSO Domains & Failures

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Since vSphere 6.5 came along we have deprecated a PSC/SSO topology that I have seen customers deploy quite frequently, therefore I wanted to quickly explain what has changed and why.

Since vSphere 6.5 it is no longer possible to re-point a vCenter server between SSO sites – See VMware KB 2131191

This has a big knock on effect for some customers as traditionally they only deployed a single PSC (Externally) and a single vCenter at each site. In the event of a failure of the PSC at site 1 the vCenter server at site 1 could be re-pointed to the PSC in Site 2. This would then get you back up and running until you recovered the failed PSC.

However in vSphere 6.5 this is no longer possible – If you have two SSO sites lets call them Site 1 and Site 2 you cannot re-point a vCenter server between the two sites. So if you only had a single PSC (think back to the above example and vSphere 6.0) you would not be able to recover that site successfully.

So how do I get round this?

Deploy two PSC’s at site and within the same SSO site/domain (See the below diagram) you don’t even need to use a load balancer, as you can manually re-point your vCenter to the other PSC running at the same site in the event of a failure.

Therefore when deploying multiple SSO sites and PSC’s across physical sites consider the above and make sure you are deploying a supported and recoverable topology.

For a list of supported topologies in vSphere 6.5 and for further reading please see VMware KB 2147672

 

Horizon View Composer Service (4 of 7)

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VMwareHorizonView

The View composer service is responsible for the creation and provisioning of the Virtual Desktops within vCenter.

viewcomposer

Provisioning

  • Create a VM in vCenter with the View Agent installed (the Parent VM),
  • Shutdown the VM and create a Snapshot,
  • In View Manager, create a new Automated linked-clone pool.

What happens next (KB 1021506);

  1. View Manager creates the linked-clone entry in View LDAP and puts the virtual machine into the Provisioning state.
  2. View Manager calls View Composer to create the linked clone
  3. The View Composer Server creates the machine account entry in Active Directory for the new clone and creates a random binary password for the newly created computer account.
  4. If a replica for the base image and snapshot does not yet exist in the target datastore for the linked clone, View Composer creates the replica in the datastore. If a separate datastore is configured to store all replicas, the replica is created in the replica datastore. (In View 4.5 and later, replicas can be stored in a separate datastore.)
  5. View Composer creates the linked clone using the vCenter Server API.
  6. View Composer creates an internal disk on the linked clone. This small disk contains configuration data for QuickPrep or Sysprep. The disk also stores machine password changes that Windows performs every 30 days, according to the policy setting. This disk data ensures that domain connectivity is maintained when a checkpointed desktop is refreshed.

Recompose

A recompose operation lets the administrator preserve the View Composer persistent disk and all user data inside this disk while changing the operating system disk to a new base image and snapshot. With recompose, an administrator can easily distribute operating system patches and new software to users. Recomposing between major operating system versions are not supported (XP >Vista, XP >Windows7, Vista >Windows7).

Because a new operating system  disk is created during a recompose, the clone is also customized again during the recompose operation. When the customization is completed, View Manager takes a new snapshot.

These steps occur during a recompose operation:

  1. View Manager puts the linked clone into the Maintenance state.
  2. View Manager calls the View Composer resync API for the linked clones being recomposed, directing View Composer to use the new base image and snapshot.
  3. If a replica for the base image and snapshot does not yet exist in the target datastore for the linked clone,View Composer creates the replica in the datastore. If a separate datastore is configured to store all replicas, a replica is created in the replica datastore.
  4. View Composer deletes the current operating system disk for the linked clone and creates a new operating system disk, linked to the new replica.
  5. The rest of the recompose cycle is identical to the customization phase of the provisioning and customization cycle.