The complete guide to VDI storage management

Boosting virtual desktop performance with storage finesse

Storage load affects virtual desktop performance more than any other factor, making VDI storage management a critical task.

To get the best end-user experience from your virtual desktops, you need to choose the right storage system. First, decide whether you want to use the existing array or buy all new storage. There are lots of vendors and capacity planning tools to consider. You should also take into account IOPS requirements, costs and virtual machine (VM) provisioning needs.

Once you've got the right storage in place, keep tabs on the ups and downs of your virtual desktop infrastructure (VDI). Virtual desktop loads are more inconsistent than physical ones, depending on user activity, and storage bottlenecks are common.

In this guide, learn best practices for selecting, configuring and allocating VDI storage to get the strongest performance out of your environment.

Table of contents:

Choosing VDI storage

Do you need a new storage array for VDI?
Virtual desktops have very unpredictable workloads. Before you virtualize desktops, determine your VDI storage requirements to see whether your existing array can handle the extra load. In a small environment, you could get away with using your current array, but a larger one might require a new system. You could also segregate the physical server load and VDI load on the same system.

Getting a grip on storage for desktop virtualization
As you plan your VDI storage needs, determine the IOPS requirements of each user. Make sure to study all times of day and include all types of users in your assessment. You should also use capacity planning tools to plan for future growth (i.e., more virtual desktop users). Finally, consider storage allocation techniques such as data deduplication and thin provisioning.

Considerations for selecting VDI storage
There are lots of storage choices, but not all will suit your virtual desktops. Fibre Channel may make your deployment too expensive, but iSCSI and network-attached storage may not cover your IOPS needs. You also need to figure out the best number and size of logical unit numbers and determine the read/write ratio of your desktops to choose a RAID level.

VDI storage options: Flash appliances, bundled stacks
Storage takes a bigger capacity hit in a virtual environment than in physical systems because the desktop is centrally stored instead of living on the local device. Some vendors now offer solid-state drives (SSDs) with VDI storage options to account for higher IOPS. Beyond the traditional storage area network (SAN), managers should consider bundled stacks, all-flash systems or appliances that combine SSDs and hard drives.

Calculating costs and capacity

Understanding IOPS ups and downs
For solid VDI storage management, you need to know how IOPS affect storage performance. The amount of IOPS a virtual desktop requires depends on the services and applications the user is running at a given time. To help measure overall usage, determine how much will be required during the logon process and how the apps are delivered.

Why dollars per gigabyte and IOPS don't mix
If you're using a SAN, you'll find that costs increase exponentially when desktop virtualization enters the picture. The price per VM, in addition to snapshots, replication and redundancy, can make your VDI storage costs skyrocket. To still achieve optimal desktop performance, you can spread the load across more disks or SAN frames.

The hidden costs of VDI storage
You probably already know that VDI storage management costs include the initial capital expenditure for the system and any related power and cooling costs. You might not realize, however, that "fat" desktops (which include all the configuration files, OS, apps and user data) require more storage than thin desktops. Thin desktops also allow IT managers to automate administration tasks and patching.

Calculating storage needs for VDI
To calculate storage for VDI, don't just figure out the size of a virtual hard drive (VHD) and multiply that by the number of virtual PCs. In addition to VHD storage needs, you have to calculate storage for backup and disaster recovery situations, as well as anticipated growth.

VDI storage configuration and allocation
In this webcast, virtualization expert Eric Siebert explains how to configure VDI to meet storage demands and what storage array features you should look for from vendors. The most important aspect of desktop virtualization is the user experience, so properly allocating storage is critical to get optimal performance -- especially during peak usage periods.

VDI storage management challenges

Solving VDI storage problems
If you're running media-heavy applications on virtual desktops, you might find that performance suffers. Solid-state storage might be just the trick, which many vendors offer as appliances. To reduce storage requirements further, consider local caching technologies that use server-attached storage. There are even ways to optimize your existing SAN if it runs into problems during boot storms.

Pros and cons of storage virtualization for virtual desktops
To decrease costs and increase performance, you might even consider storage virtualization in a VDI environment. Storage virtualization adds a layer of abstraction between the virtual desktop or underlying hypervisor and the physical storage device. But watch out: This can increase long-term support costs and add complexity.