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Mar 08 2015

How to Recover Linked Clone Desktops in a DR Site

Disaster Recovery for Horizon View has always been a hot topic. To this date VMware still doesn’t provide an official methodology to protect virtual desktops. Equally, VMware Site Recovery Manager does not support Linked Clone desktops created by Horizon View Composer. Conversely, Full Clone desktops can be protected using native storage replication or vSphere host-based replication.

Nutanix provides native asynchronous and synchronous VM-Centric replication, automatically registering and powering on desktops with the destination vCenter, making them available for use in the recovery site. When the recovery event is over Nutanix applies all VM block changes back to the primary site and re-initiate the workload. The video below I published a while back and demonstrates the workflow with ‘Full Clone’ desktops.

 

 

However, most Horizon View deployments are currently using Linked Clones desktops provisioned with View Composer. Linked Clone desktops can be of non-persistent (aka floating) and persistent types. For the non-persistent type no protection to the virtual machine is required and there are multiple ways to enable protection and replication of user data and profiles. Back in 2010 I wrote an article entitled VMware View Disaster Recovery Scenarios & Options and the options available at the time are still pretty much unchanged.

What many administrators realized is that while using Linked Cloning many desktops cannot be simply dismantled, refreshed or recomposed due to user installed applications, files not saved to correct locations, log retention policies etc. Often times I hear administrators telling me they like the Linked Cloning management capabilities, but in practice desktops cannot be destroyed.

To this date I have not seen a solution that will properly backup and replicate Linked Clone desktops with full understanding of View Composer intricacies, including replica disk paths, vmx and datastore paths, internal and non-attached disks, etc.

 

I have been working directly with the ingenious Nutanix engineering team and I am happy to announce that your problems are over.

 

Nutanix 4.1 (GA) has a complete understanding of the Horizon View Composer intricacies and is able to backup/restore and replicate Linked Clone desktops to a recovery site. Additionally, when in recovery mode it is possible to power on those desktops (Nutanix automatically register VMs with vCenter in the recovery site) and make use of them. When the recovery event is over all changes are replicated back to the primary site and life returns to normal.

Desktops are not the only resources needed when in recovery mode; you will also need Connection and Security Servers, Active Directory, SQL or Oracle Databases. All components, if not already available in the recovery site, can be replicated and made available for use. Please note, that DNS name resolution and IP translations for Connection and Security Servers must remain the same to allow desktop agents to communicate properly. For this reason it is suggested use of stretch layer 2 technologies.

 

There are couple guidelines to be observed.

 

  1. Limit Linked Clone desktop pools to a maximum of 50 desktops and ensure desktops are member of a unique Nutanix Consistency Group and Protection Domain. Multiple backup and retention schedules may be created. (Nutanix is working to increase the 50 desktops per PD limitation)
  2. Before executing a ‘planned’ recovery the administrator must disable Horizon View desktop pools to avoid automatic power-on of desktops that may prevent them from being migrated to the recovery site.
  3. When in recovery mode users can access desktops and the Connection Broker is able to execute power operations. However, in recovery mode no View Composer operations such as Refresh and Recompose can be executed. Once the desktops are migrated back to the primary site all operations are once again available.
  4. Nutanix will soon release a best practices guide.

 

Truthfully, it is that simple to provide backup/restore and recovery capabilities to Horizon View Linked Clone or Full Clone desktops with Nutanix.

 

This article was first published by Andre Leibovici (@andreleibovici) at myvirtualcloud.net

6 comments

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  1. Simon Long

    Hey Andre, this is cool stuff, thanks for sharing.

    Quick question. You mentioned that when in Recovery mode, Refresh and Recompose can no be used. Does this include ‘Refresh on Logoff’ and Delete on Logoff’ operations?

  2. Andre Leibovici

    Hi Simon, that is correct. No Linked Clone operations when running in the recovery site. If you are doing ‘Refresh or Delete on logoff’ you are doing non-persistent desktops; thefore no VM backup and replication is required. This is for those linked clone desktops that need to persist sessions. Hope that make sense.

  3. Simon Long

    Yeah, it does. Thanks. I can’t wait to see a demo!

  4. ldhoore

    Andre,

    Thanks for sharing.

    You write that VMware Site Recovery Manager does not support Linked Clone desktops created by Horizon View Composer.

    The VMware SRM documentation however states “Array-based replication supports the protection and recovery of virtual machines that are linked clones”
    Did they forget to mention that Linked Clone desktops “created by Horizon View Composer” are not supported?

    (http://pubs.vmware.com/srm-58/index.jsp#com.vmware.srm.admin.doc/GUID-084C089D-9689-4F34-9A75-8AFB980A725E.html?resultof=%2522%256c%2569%256e%256b%2565%2564%2522%2520%2522%256c%2569%256e%256b%2522%2520%2522%2563%256c%256f%256e%2565%2522%2520)

    There is also a whitepaper “VMware View Infrastructure Resiliency” with a Failover Procedure for Floating Linked Clone Desktops.
    I find the title of this section very confusing because within the article they state “To minimize the number of recovery steps needed, storage replication is required only for the base image
    virtual machine. All other components are rebuilt”.
    So this statement does not make it clear of it is supported or not.
    http://www.vmware.com/files/pdf/techpaper/vmware-view-vcenter-site-recovery-manager-disaster-recovery.pdf

    I find the VMware documentation very confusing and not at all clear.
    I have been looking for an document/article/… from VMware stating that VMware Horizon View Linked Clones are not supported with SRM, but I can not find it.

    Can you shed some light on this?

  5. Andre Leibovici

    ldhoore, good points.

    The document you mention says:
    – vSphere Replication does not support the protection and recovery of virtual machines that are linked clones.
    – Array-based replication supports the protection and recovery of virtual machines that are linked clones if all the nodes in the snapshot tree are replicated.

    You can replicate the entire LUN or Volume with traditional 3-tier storage (SAN), however I am not sure it is possible to bring entire the solution up and running on the recovery site due to View Composer integration, relationship with external databases and datastore paths for the replica.

    In regards to Floating desktops, those are supported when not used with persistent sessions. Therefore, it is possible to replicate only the user roaming profile.

    Also, SRM will not support View Composer Linked Clones AFAIK.

  6. Sahil

    We are in similar fix how to recover linked clones at DR, it’s veiw 6.0.1 deployment , as resource pools got deleted in vCenter(no backup of snaphot tree), and all vm are in root. Vmware support suggested to do restoration of vCenter db! Any headways?

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