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Can your storage system auto-tier storage at the block level? That answer is likely no.  Most storage vendors allow you to move whole LUNs between different tiers of storage but they lack the intelligence or technology to move individual blocks.  Why is this cool and desired?  Well, the vast majority of VMware Virtual Machines are stored on SAN volumes formatted with VMFS, VMware’s virtual machine file system.  On this single SAN volume, there can be many virtual machines.  For a server deployments, 10-20 VM/VMFS is common and for VDI deployments it could be up to 64 VMs/VMFS.  So the on-going problem for all VMware administrators has been how do you ensure each of these VMs has the performance it needs when some VMs are very active and others are not?  That’s a valid question for less capable storage systems for most vendors.  But a better question is, “How can I provide tier 1 storage performance to only the blocks that need it?”  Only Compellent can provide a simple answer to that question with their automated tiered storage.

If you take a typical windows VM you have plenty of unused system files and stale data that is not ever accessed.  In the case of a Microsoft Exchange mail server, think of all the mail that is older than a 1 day old.  It is rarely accessed, so until it can be permanently archived to cheaper tiers of storage, it makes great sense to let the Compellent Storage Center automatically move the data that is rarely accessed to lower tier of primary storage, saving money on tier 1 storage and helping maximize the performance.  Since Compellent has a unique Dynamic Block Architecture, it can “see” inside the vmdk and identify blocks that are rarely used and move them to lower, cheaper tiers of storage without administrator intervention, scripting or creation of snapshots on VMs to facilitate storage vmotion.

One blog post can’t really do Compellent technology justice.  I’d invite you to view the announcement of the new features of their fifth version of Compellent Storage Center here.  

 And as always, please feel free to comment on this post by hitting me on Twitter, with @vSeanClark. I’ve been working with Compellent in VMware deployments for over 2 years now and have plenty of Compellent/VMware goodness to share with you.