When it comes to testing the upgrade process of an ESXi host or vCenter version, it can be a challenge to ensure that it will operate at the best possible level. Further, the traditional storage environment doesn’t usually move as quickly as software environments in terms of upgrades. This is especially true with virtualization, as a major upgrade every two years seems normal.

The vStorage APIs for Array Integration (VAAI) are an important advance in virtualization technologies. With VAAI, a number of heavy I/O tasks are deferred to the storage array instead of having the ESXi server do all of that work and put duress on its I/O channels and the storage fabric. With vSphere 4, the first wave of VAAI support was delivered, and a number of storage products supported it. If the storage resource supported VAAI, it was pretty easy to spot within the vSphere Client. Figure A shows a disk resource that supports VAAI.
Figure A

Click the image to enlarge.

The good news is that vSphere 5 supports NAS storage protocols. Previously, only block storage protocols of iSCSI and fibre channel that leverage the VMFS file system were supported with VMFS. For NFS resources, hardware accelerated cloning (sometimes called bulk copy) and space reservation for pre-allocating virtual disk space at creation. This allows lazy-zeroed thick provisioning from the host with the array aware of the growth pattern. Many of the VAAI features are explained in the vSphere 5 Performance Best Practices Guide (page 11 of the PDF).

Now that you know the basics about VAAI, there are some steps you can take to ensure an optimal migration to vSphere 5:

  • Ensure storage firmware is up to date: Most SAN and NAS systems have updates that may be just as frequent as operating systems and may need to be updated.
  • Ensure host BIOS and HBA firmware is up to date: These components, while they won’t prohibit VAAI from working, are definitely a piece of the infrastructure that needs attention. I frequently say, “Never underestimate the value of a good firmware upgrade.” These components are difficult to test, but this is a critical task of infrastructure administration.
  • Hold off on provisioning additional VMFS-3 volumes: It is worth ensuring that the VMFS-5 environments are as clean as possible and as little mixing as possible goes on after the upgrade. Further, you want all datastores to use the unified 1 MB block size instead of having some at 2, 4, or 8 MB and 1 MB.
  • Ensure all hypervisors are as up to date as possible: If any VI3 installations exist, they should be pushed to version 5 or at least version 4. The main reason to hold on to a version is for hardware compatibility reasons, so work to ensure all hosts can take advantage of VAAI.

VAAI offers a number of performance features for vSphere environments and, due to equipment lifecycles, now may be the time that new arrays are purchased that support VAAI. If so, you should ensure that the full line of components in the vSphere infrastructure is ready to support these new features.

Have you made the jump to VAAI? If so, what storage tips have you started with the new capabilities of VAAI and vSphere 5? Share your comments below.