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Thursday, July 15, 2010

YES WE CAN! VDI with local storage AND high availability

There is a debate raging on and elsewhere as to whether local storage can be used with VDI, and if it is good enough.

This strikes at the core of why we founded Kaviza, so here are our perspectives. Folks are debating between 2 options:

Option 1: Shared storage. You get high availability, dynamic load balancing, etc but cost is high.

Option 2: Local storage with traditional VDI. None of the above but cheap. 

They are not talking about Option 3. Where is Option 3??

The conclusion here seems to be that Option 2 is good enough for VDI.  Or is it? What are you losing? The main reasons people go to VDI is to streamline management, and increase desktop uptime.  Will Option 2 give these?

i) What happens when you go beyond 1 server? Do you manage all the desktop images manually on each server? Keep them up-to-date? Statically provision to each server?

ii) What happens when a server fails? These are not server workloads, but users care about their desktops being up. No redundancy means downtime.

The critical question is whether we can retain the inexpensive, high performance, and obvious choice of local storage in VDI when we need scalability and high availability.  Can we get a scalabile, highly available desktop service without the high upfront and ongoing costs of shared storage?

So, what if you had an Option 3?

Option 3: Local storage with a new VDI architecture designed to deliver high availability and dynamic load balancing on DAS.

This can be done - in fact, it's exactly what Kaviza has.  Again, this is not aimed to be a plug but to technically highlight how an architecture can achieve DAS and HA.

Kaviza was founded on the notion that those features critical to VDI can be retained in a distributed, local-storage architecture by implementing an abstract common store of the images through a desktop-specific management layer.

Kaviza maintains the desktop images locally on each server.  The actual desktops running on each server, generally as thinly cloned VMs, use the local images solely.  As admins go through image lifecycles to update and patch the base images, those changes are automatically transferred to the local storage on the other servers that need them.

Thus the appearance to the administrator is that there is a single store common to the entire installation.  But the implementation of the store is entirely on local disk.

As new servers are added to the installation, those images that need to be sent to them are automatically transferred there.  And if a server is lost due to failure, the desktops running on that server are automatically reprovisioned on surviving servers.  Hence Kaviza supplies both scalability and high availabilty using only inexpensive local storage.

For many customers, desktop forklift to justify high investment in traditional VDI is a non-starter. What they want is a solution that gives them an immediate return on their investment for every refresh cycle, no matter if its 30 desktops or 3000.  For these customers, local storage is the only way to go.  And Kaviza has a comprehensive virtual desktop solution that linearly scales throughout that range at a constant price per desktop.

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posted by Kumar, Kaviza CEO at


Blogger jeff said...

So, can anyone explain how you use local DAS to store user data in a manner that is fast to access, easy to partition for multiple users, secure and immune to data loss? Or is this not the case and actual user data (music, photos, documents, etc.) must be stored on a NAS? An explanation here would be fantastic as I do not see this issue addressed or explained anywhere.


July 27, 2010 at 2:29 PM 

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