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NetApp Flexclones, VirtualCenter Templates, Deduplication, and NFS for VDI

For my project, 5 TB of raw disk space on a NetApp FAS3020 resulted in roughly 2.5 TB of usable NFS volumes. Sacrificing half the storage as overhead (for both ESX and NetApp) might seem like a big hit to take at first, but when you consider what you are able to do in the remaining useable space it can change your opinion. In my recent experience, after combining the features of Flexclones, VirtualCenter (VC) templates, deduplication, and NFS the remaining 2.5 TB enabled a virtual desktop infrastructure (VDI) storage solution for over 80 virtual machines (VMs). Your results may vary, but the concepts discussed in this post provide for a scalable and flexible design.

Although this post discusses NetApp, I imagine any NFS filer with similar features could be used in this same fashion. I’m curious for feedback on not only this solution, but the pros and cons of other vendor’s features in a similar scenario.

Here’s a logical diagram illustrating a NFS volume strategy followed by some high level details of each volume.

Click the image for a larger version.

2K3_Master – this is the home of a VM with a base install of Windows 2003 Standard. This volume and the VM it contains will be Flexcloned as new volumes for other Windows 2003 servers. After building the VM , this volume will not be mounted by the ESX hosts. To start the VMware VDM server will be the only Server created from this volume.

XP_Master – this is the home of a VM with a base install of Windows XP without any applications. This volume and the VM it contains will be cloned 4 times to create the 4 departmental template VMs. After building the VM, this volume will not be mounted by the ESX hosts.

ISO – a volume to store .iso files of installation and application CDs used by all of the VMs.

VDM – this is the home of the VMware VDM Server virtual machine created from a Flexclone of the 2K3_Master volume. The advantage of this Flexcloned volume is that it takes up no additional storage space to create, and the VM is thin provisioned by default (because it’s on NFS) and will only consume the space needed to install and configure VMware’s VDM instance.

XP_VM volumes for Marketing, Finance, Contractors, and IT Dept – 4 different volumes that are each created from a Flexclone of the XP_Master volume. Each volume will start with the default configuration of the XP VM, but then customized with unique application sets. The resulting 4 department VMs will be turned into VirtualCenter gold image templates. Desktop VMs will be deployed on these volumes from the VirtualCenter templates. Although the gold image departmental template will take up no extra space and be a thin provisioned .vmdk, the desktop VMs that are deployed via VirtualCenter cloning will be thick .vmdks. Deduplication will be enabled to reclaim as much space as possible.

SWAP – the templates, the desktop vms, and the server VM will all separate the Windows pagefile on to a dedicated .vmdk which will be stored on this volume. This is necessary to be able to exclude this transient data when scheduling backups and/or SAN replication.

Other General Design Notes:

  • The NFS volumes can be extended or reduced as needed by adding more shelves of disks to the aggregate. (another term for the array)
  • The 2K3_Master and XP_Master volumes can be Flexcloned to new volumes for future server or desktop VMs not currently provisioned in this solution. 32 volums is the max number of volumes ESX can connect to, however.
  • VirtualCenter VM cloning was considered less complex by the IT staff (automated, sysprep-ed and customized deployment of new VMs) than duplicating VMs via NetApp volume Flexcloning
  • The NetApp FAS3020 has a volume limitation of 1 TB for deduplication. Upgrading to a larger model increases the deduplication limit as shown in the following table provided by NetApp:

For some additional reading on NetApp NFS for VI, Flexclones, and deduplication check out the following posts by Scott Lowe. Scott has written a lot about NetApp Flexclones, configuring ESX for flexcloned volumes, and the pros and cons of SAN cloning compared to VirtualCenter cloning.

Also check out the following NetApp technical reports: (the design discussed in the post is basically a hybrid of these 2 reports. 3612 is for VDI recommendations, and 3428 is for server VM recommendations.

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