Mixed vendor storage virtualization is one of those technologies that looks good on paper but has not materialized in execution. One of the mistakes that early storage virtualization vendors made was that they focused primarily on the cost savings aspect of storage virtualization. The message was you could buy the cheapest storage system available because you no longer needed the storage services (snapshots, replication) from the larger, more expensive storage vendors.
While it was true that you could drive down the cost, the reality was that simplicity of management and implementation was a larger concern for most customers. It seemed safer, more reliable, and simpler to use the turnkey solutions provided by the storage manufacturers. Additionally the turnkey storage manufacturers began adding storage virtualization functionality like thin provisioning and wide striping (using all the available disks to create a RAID volume).
There are two key capabilities, though, that may change the course of storage virtualization and make the mixed vendor storage infrastructure a reality in more environments. The first is the ability--and more importantly thanks to solid state storage, the desire--to move data among different types of storage. This can be done via automated tiering or virtual machine storage migration capabilities integrated into the hypervisors. With data motion capabilities, a mixed vendor environment is no longer just a cost savings advantage, it is also a performance enhancement advantage.
This data movement capability between tiers is, of course, available from some turnkey providers as well but it may be more valuable in a mixed vendor environment when powered by storage virtualization. Despite what turnkey vendors may claim, no single vendor makes the absolute best system for every performance tier and every data center. For example as we describe in our article "The Importance of SSD Architecture Design" not all SSDs are created equal. Storage virtualization provides you with the flexibility to choose the fastest performing solid state storage system for the task at hand, if the ultimate in high performance is what you need.
The second key capability is the ability to leverage the hypervisor as we discussed in our article "The Storage Hypervisor." First generations of mixed vendor virtualization systems came either as software that needed be loaded on a dedicated server or as a purpose-built appliance. The developer had to worry about developing failover and clustering capabilities and you then had another server to acquire and another variable to manage. The storage hypervisor approach means that the storage virtualization process is either provided by the hypervisor itself or is a VM on the virtualization host. This allows you to leverage the availability and scale already built into the server virtualization platform.
Finally there is still the cost savings available in buying the right storage system for the right purpose. You may need a small solid state appliance for performance sensitive situations, but most VMs will see all the performance they need from a midrange, cost effective array.
Where does this leave the turnkey storage vendors? There will still be a role for them, as not everyone will be comfortable mixing storage vendors in their infrastructures. For the most part they will have to evolve by either continuing to out-enhance their storage virtualization software competitors, by becoming mostly software companies and more hardware agnostic, or by becoming great hardware companies and being software agonistic. We will dive into the details of each of these options in an upcoming entry.
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