The Missing Link in Software-Defined Storage

At this year’s VMworld 2012, held in San Francisco at the Moscone Center, the “software-defined data center” was a major topic.  The idea is appealing:  make the entire IT infrastructure completely fluid so that all resources – compute, network, and storage – can be quickly and easily allocated or reclaimed to meet dynamic business requirements (including predictable performance), thereby extending the flexibility and cost savings benefits virtualization provides across the entire IT infrastructure.

If you take what the server hypervisor did for compute resources as the analogy - allowing a single control point to manage the dynamic allocation of CPU and memory resources that are consistently used very efficiently – this part of the puzzle has been "software-defined" and solved.  A solution to this problem for the network side is well on its way to being solved - note VMware’s recent acquisition of Nicira, and Oracle’s smaller purchase of Xsigo, as steps towards allowing more of the IT infrastructure to be managed as purely virtual resources directly from the hypervisor.

It’s clear that this same transformation needs to happen with storage.  In essence, software-defined storage is the missing link, the last hardware bridge to cross on the path to the software-defined data center.

So just what is “software-defined storage”?  Well, if you stick with the earlier analogy we drew with the server hypervisor and what it did for compute resources, storage virtualization is clearly part of it but is not sufficient by itself.  Server hypervisor technology not only made compute resources fluid and much easier to manage, it also significantly increased the utilization of those resources to cut the costs of the compute hardware infrastructure.  For servers, it was the server consolidation that virtualization enabled that provided this huge boost in utilization, effectively allowing customers to support the same application workloads with much smaller and less costly compute infrastructure.

Storage resources clearly DO have to be virtualized, but the “improved utilization of existing resources” question manifests itself a little differently.  If you’ve played with virtual environments, you already know that storage performance suffers in most type 1 hypervisor deployments relative to what you’d expect it to be based on your experience with storage on physical servers.  This “VM I/O blender” issue is discussed at length in other blogs on this site (and also by other vendors who have noted it) so I won’t go into it here, but the 30% - 50% storage performance slowdown that virtual administrators experience in these environments touches not only runtime performance, but your ability to use storage capacity optimization technologies like thin provisioning, valuable operational features like snapshots and clones, and quickly provision the storage you need. 

You have 15K RPM disks in your environment that should be capable of handling 180 IOPS (on average) but may actually only be delivering (from your guest VMs’ points of view) 30-45 IOPS.  This is due in part to the randomness and write-intensivity of most virtual workloads (the VM I/O blender effect) as well as thin provisioning and snapshot/clone implementations.  If you could write sequentially to that same 15K RPM device, you’d find that it could deliver more like 2000 IOPS… and that’s on a per spindle basis.  How do you unlock that unused potential?

THAT’S the other challenge that you should expect software-defined storage to address.  It has to not only virtualize heterogeneous storage resources, but it also has to unlock the performance that is imprisoned within them to allow for the instant provisioning of high performance, space-efficient storage.

Over the last year, the term “storage hypervisor” has been gaining currency and adopted by vendors including IBM, NetApp, HDS, Datacore and Virsto.  Definitions of the storage hypervisor show that it can be an attractive way to deliver on software-defined storage.  But what constitutes a storage hypervisor? 

To truly be the missing link in delivering on the software-defined data center, it has to be implemented in software (so that it integrates with the native hypervisor while preserving those familiar workflows), virtualize heterogeneous storage resources to provide flexibility in allocation, and inherently increase the utilization of existing storage.  That means that it has to make your existing storage support instantly provisioned, high performance, space-efficient (read thin provisioned and zero copy clones), VM-centric (NOT LUN centric) storage objects WITHOUT requiring that you purchase higher performance or additional storage to get there.  It goes without saying that if you DO buy a higher performance or additional storage, it should speed that up too.

Virsto just recorded a webinar on this topic entitled “Software-Defined Storage:  How It Will Improve Your Virtual Environment”.  We have a storage hypervisor that runs on both vSphere and Hyper-V and delivers on the requirements above, thereby offering a way for enterprises to take that next step that transforms storage to deliver on the promise of the software-defined data center.  You can check that out here.

From a bottom-line financial point of view, what the Virsto Storage Hypervisor will do for you is give you up to 10x the performance (IOPS, throughput) on a per spindle basis that you get with your storage today, while lowering storage latencies, allowing you to cut storage costs by generally around half while meeting your EXISTING performance requirements with your EXISTING storage (or any new block-based storage if you’re embarking on a new rather than an existing project).  That storage is space-efficient, can be provisioned almost instantly (so you can spin up the high performance storage you need as fast as you can spin up a new VM), and looks like a native storage object (VMDK on vSphere, VHD on Hyper-V) so that it is managed with familiar native hypervisor workflows while delivering these benefits.

If the software-defined data center idea appeals to you, Virsto will help you get there.  If you are working your way toward that vision, Virsto will cut your storage costs by 50% and deliver highly scalable snapshots and clones for VDI, snap reverts, test and dev, rapid database clone creation, and backup.