As server and storage virtualization find their way into even small data centers, organizations are now considering virtualizing desktops, known as virtual desktop infrastructure (VDI). VDI offers tangible advantages. Because operating systems and applications are centrally-located master images rather than local instances on every user’s computer, managing these resources becomes vastly easier. The computers are thin or zero clients and therefore can be relatively inexpensive devices like iPads. Moreover, VDI keeps all data within the corporate security perimeter to safeguard against data loss or theft, especially with the proliferation of mobile devices.
VDI, however, also centralizes data storage, which puts tremendous pressure on storage systems to handle read and write demands. When users boot up in the morning and log in, or log out at the end of the day, they can overwhelm the I/O capacities of storage devices, resulting in very slow response times. Because of these “boot storms,” administrators must ensure their VDI storage meets performance needs as well as capacity needs. This is why RAID arrays, which provide fast reads thanks to their multiple disks, are a strong solution. Additionally, some RAID vendors offer solid-state drives (SSDs), which are nearly as fast as DRAM, for read and write caches. Reading master images from SSD can greatly mitigate boot storms, and data can be speedily written to SSD and transferred later to spinning disks. Moreover, RAID arrays that offer block-level data deduplication can reduce the amount of data written to disk, and solutions that support VAAI (vStorage APIs for Array Integration) quicken disk operations by offloading storage tasks from the physical servers running VMware virtualization to the storage array. The bottom line is a successful VDI implementation requires fast storage, which often means function-rich RAID.