Book Image

VMware Horizon View High Availability

By : Andrew Alloway
Book Image

VMware Horizon View High Availability

By: Andrew Alloway

Overview of this book

Table of Contents (16 chapters)
VMware Horizon View High Availability
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Functions of the View Composer


The View Composer is used to manage virtual desktops on the vCenter server. Its primary function is to track link-cloned desktops and manage the state and configuration of link-cloned desktops. Link-cloned desktops share the same OS disk, providing a significant storage saving over fully-provisioned persistent virtual desktops. Link-cloned desktops consist of a VMDK that is used to track changes to the OS disk, and a user data VMDK when configured for persistent user disks.

Fully provisioned desktops can be deployed manually by installing a Client OS on a VM or using the View Composer to provision virtual desktops that are cloned from a base. Fully provisioned desktops use the same amount of disk space as the base image if thick provisioned or if thin provisioned the OS disk usage plus the user's data.

The View Composer handles the following requests from the View Administration Console:

  • Refresh: This action restores linked clones back to their original size and state. This reduces the size of clones that can grow over time and simplifying the removal of undesirable changes to the operating system, while preserving user profiles.

  • Recompose: This action pushes a new version of an image to all users in the assigned pool. It is useful for deploying complicated software and patches that many users in a pool require. This operation also removes undesirable changes from the operating system, while preserving user profiles.

  • Rebalance: This action allows the systems administrator to manage the location of View Link-Cloned desktops. A rebalance is required to migrate View VMs to other datastores/hosts.

High Availability considerations for View Composer

A View Connection server only needs access to the View Composer for recomposing images and refreshing VMs. View only needs access to vCenter to power on/off VMs and to complete any operation that the View Composer is required for.

For small environments, it is often acceptable to have outages on the View Composer or vCenter server in the 5-30 minute range as logins and access to the View environment are not immediately affected by View Composer downtime. System administrators should be aware that this situation can eventually cause a login outage. If desktops are configured to refresh or recompose after a logoff, in the absence of a functional View Composer, the pool of desktops will eventually be exhausted. Users will not be able to start new sessions when the pool of available desktops is exhausted.

For View environments with dedicated desktops, it is possible to operate without the View Composer for days as it is very rare to require Recompose or Refresh operations.

First, we determine whether we are going to install the View Composer on a dedicated machine or on the vCenter.

The View Composer currently can only be installed on a Windows 2008 R2 or higher version server. If you are using a vCenter appliance, you cannot install the View Composer on that appliance and you will require a separate Window Server VM for the View Composer.

When vCenter is installed on a Windows server, the View Composer can be co-installed on that server. In practice, the performance requirements for the View Composer are much smaller than the vCenter Server. Since vCenter and the View Composer have similar High Availability requirements, in practice co-location should be considered best practice unless dealing with a very large View environment.

Co-locating the View Composer with vCenter considerations

If we install the View Composer on the vCenter, we only need to worry about keeping the vCenter VM and database up and running. With shared storage, we can utilize VMware High Availability to restart the vCenter and View Composer server in the event of a host failure. This solution is acceptable for smaller View environments where the vCenter is not needed 100 percent of the time, or licensing costs are a significant consideration.

In the event of leveraging only the local storage, we can use the VMware Replication Appliance to replicate the vCenter to another host. The Replication Appliance has the downside of requiring manual intervention for restarting the vCenter on the backup host. It also can potentially mean some data loss on the database in the event of a failure and potentially a call to VMware to resolve any database issues. We can also utilize a backup solution, such as VMware Data Protection or various third-party solutions, and simply restore the VM from backup. This will be much slower than the replication method described previously.

Our other alternative is to install the View Composer and vCenter database on a highly available database cluster. This requires vCenter 5.5 or higher to support Microsoft SQL clusters or Oracle clusters. This has the upside of not losing data in the event of a failure but requires careful planning to ensure that there are not two instances of the vCenter or View Composer services running. We can choose to either run two vCenter/View Composer servers using a third-party Application Cluster software in an Active/Backup scenario or we can repeat the Replication Appliance scenario and simply have a cold backup vCenter / View Composer VM ready on our second node. VMware currently supports using Microsoft Cluster Services to provide High Availability for the vCenter. You can utilize solutions from the following vendors using their documentation on the process:

  • MSCS (Microsoft Cluster Services)

  • Microsoft SQL Server 2012 or 2014 AlwaysOn

  • Oracle Real Application Clusters (RAC)

  • VCS (Veritas Cluster Services)

  • Symantec ApplicationHA

Note

Check out the following VMware knowledge base article for more details: http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1024051.