Managing storage for virtual environments: A complete guide
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Servers, network devices and storage need to be more hypervisor-aware to keep up with today's expanding virtual infrastructures. Fortunately, some storage vendors have recognized this need and developed virtualization-aware storage that could benefit your infrastructure.
Bare-metal hypervisors virtualize everything on the server, and the underlying guests never know the difference. As these hypervisors have matured, however, they have asked a bit more from the server hardware. For example, the latest version of VMware vSphere now requires a 64-bit CPU and either an Intel VT or AMD-V CPU virtualization extension. These CPU features allow the software -- the vSphere or Hyper-V hypervisor -- to work with the hardware in ways not previously possible. Now that the CPU cooperates with the hypervisor, storage should follow suit.
How hypervisor and storage cooperate with VAAI and VASA
Today, VMware's vStorage APIs for Array Integration (VAAI) and Microsoft's Offloaded Data Transfer allow for some cooperation between the storage and the hypervisor. Many enterprise storage vendors have also adopted VMware's vStorage APIs for Storage Awareness (VASA).
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VAAI speeds common hypervisor storage-related operations, such as virtual machine (VM) cloning or disk space reclamation. When you perform a snapshot of a VM located on a VAAI-capable array, you'll prevent locking on the entire logical unit number (LUN) unique identifier.
VASA, on the other hand, lets storage report to the hypervisor on the storage capabilities. The hypervisor benefits from these storage reports, but storage could also benefit from VM reports. With that knowledge, the storage could offer the most important VMs the best performance and give the virtualization and storage administrators per-VM statistics.
Let's look at some of the benefits admins can reap from virtualization-aware storage.
The benefits to hypervisor-aware storage
As an admin, you want to know how many IOPS each VM generates, which VMs are write-intensive, how many IOPS the whole virtual infrastructure demands and how many VMs are using that storage. Virtualization-aware storage provides you with that information.
Another benefit to virtualization-aware storage is end-to-end bottleneck identification from the perspective of the storage. Previously, admins blamed the storage for problems they couldn't identify. Now, storage admins and virtualization admins with access to the storage can get more accurate storage statistics. The storage can then combine its knowledge of the virtual infrastructure to quickly solve performance problems and identify bottlenecks. Figure 2 shows latency identification from Tintri Inc.'s storage management interface.
Finally, virtualization-aware storage goes beyond statistics to actually perform operations on virtual machines, thanks to its connection to vCenter. For example, traditional storage can only take a storage snapshot on an entire LUN. Tintri, on the other hand, can take a snapshot or clone an individual VM from the storage layer.
Tintri, Tegile Systems and Nutanix all provide hypervisor-aware storage, but all hardware vendors must create more virtualization-aware products to keep up with evolving and maturing virtual data centers.