Saturday, 27 August 2011

What the Heck Is a “Storage Hypervisor?”

Our friends at DataCore ran a press release yesterday
positioning the new release (v8.1) of SANsymphony-V as a “storage hypervisor.” On the surface, that may just sound like some nice marketing spin, but the more I thought about it, the more sense it made – because it highlights one of the major differences between DataCore’s products and most other SAN products out there.

To understand what I mean, let’s think for a moment about what a “hypervisor” is in the server virtualization world. Whether you’re talking about VSphere, Hyper-V, or XenServer, you’re talking about software that provides an abstraction layer between hardware resources and operating system instances. An individual VM doesn’t know – or care – whether it’s running on an HP Server, a Dell, an IBM, or a “white box.” It doesn’t care whether it’s running on an Intel or an AMD processor. You can move a VM from one host to another without worrying about changes in the underlying hardware, bios, drivers, etc. (Not talking about “live motion” – that’s a little different.) The hypervisor presents the VM with a consistent execution platform that hides the underlying complexity of the hardware.

So, back to DataCore. Remember that SANsymphony-V is a software application that runs on top of Windows Server 2008 R2. In most cases, people buy a couple of servers that contain a bunch of local storage, install 2008 R2 on them, install SANsymphony-V on them, and turn that bunch of local storage into full-featured iSCSI SAN nodes. (We typically run them in pairs so that we can do synchronous mirroring of the data across the two nodes, such that if one node completely fails, the data is still accessible.) But that’s not all we can do.

Because it’s running on a 2008 R2 platform, it can aggregate and present any kind of storage the underlying Server OS can access at the block level. Got a fibre channel SAN that you want to throw into the mix? Great! Put fiber channel Host Bus Adapters (HBAs) in your DataCore nodes, present that storage to the servers that SANsymphony-V is running on, and now you can manage the fibre channel storage right along with the local storage in your DataCore nodes. Got some other iSCSI SAN that you’d like to leverage? No problem. Just make sure you’ve got a couple of extra NICs in the DataCore nodes (or install iSCSI HBAs if you want even better performance), present that iSCSI storage to the DataCore nodes, and you can manage it as well. You can even create a storage pool that crosses resource boundaries! And now, with the new auto-tiering functionality of SANsymphony-V v8.1, you can let DataCore automatically migrate the most frequently accessed data to the highest-performing storage subsystems.

Or how about this: You just bought a brand new storage system from Vendor A to replace the system from Vendor B that you’ve been using for the past few years. You’d really like to move Vendor B’s system to your disaster-recovery site, but Vendor A’s product doesn’t know how to replicate data to Vendor B’s product. If you front-end both vendors’ products with DataCore nodes, the DataCore nodes can handle the asynchronous replication to your DR site. Alternately, maybe you bought Vendor A’s system because it offered higher performance than Vendor B’s system. Instead of using Vendor B’s product for DR, you can present both systems to SANsymphony-V and leverage its auto-tiering feature to automatically insure that the data that needs the highest performance gets migrated to Vendor A’s platform.

So, on the back end, you can have disparate SAN products (iSCSI, fibre channel, or both) and local storage (including “JBOD” expansion shelves), and a mixture of SSD, SAS, and SATA drives. The SANsymphony-V software masks all of that complexity, and presents a consistent resource – in the form of iSCSI virtual volumes – to the systems that need to consume storage, e.g., physical or virtual servers.

That really is analogous to what a traditional hypervisor does in the server virtualization world. So it is not unreasonable at all to call SANsymphony-V a “storage hypervisor.” In fact, it’s pretty darned clever positioning, and I take my hat off to the person who crafted the campaign.

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