Evaluating VDI storage options
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When VDI performance isn't up to par, you're probably going to blame the network or storage. To see a real change in performance, focus on storage -- and prepare to invest.
Slow boot times, application launch times, shut down times and data access times all conspire to make users less than happy with their shiny new virtual desktops. VDI performance is affected by three elements: network throughput, processor capabilities and storage performance. Dealing with each of these elements requires a different approach and affects your budget differently.
Before we dig into improving storage performance, let's look at how the network factors in.
Network and processor enhancements fall short
Improving network performance may involve upgrading switches, deploying WAN and LAN accelerators, purchasing more bandwidth, deploying Quality of Service and so on. Any of those attempts to improve performance usually means downtime, increased costs and a significant investment in time and services. However, performance gains are not guaranteed, especially for remote users that rely on external network connections.
Processor performance also falls into the same grey area. Increasing processing power usually involves upgrading the physical processors in servers, along with the RAM. For many, swapping out CPUs and RAM proves to be inefficient and costly, especially compared to simply replacing servers. However, for most enterprise networks, replacing a bunch of servers is anything but simple, and the performance gains may not justify the expenses, downtime and other tasks required.
Bringing in SSDs
Network storage is the one path left that can really increase VDI performance. However, there is a symbiotic relationship between speed and cost -- the faster you want storage to go, the more it can cost, making ROI an important element of VDI performance management.
VDI clients use prodigious amounts of storage, because each virtual machine requires a virtual hard drive for the guest OS, the applications and so on. That translates to gigagbytes of storage committed to each virtual host. Ever increasing storage needs become the catalyst for investment -- typical daily VDI events, such as provisioning, booting, shutdowns and application loading require extensive storage I/O capabilities. What's more, those are the very events that have the greatest perceived impact on users.
Plus, any improvements to storage performance have a positive impact on most every operation, ranging from backups to application performance to business analytics. With that in mind, you can see how high speed storage technologies such as solid-state drives (SSDs) may offer the best bang for the buck in your organization.
With prices falling, capacities increasing and reliability on the rise, SSDs are beginning to make a lot of sense for VDI deployments. When a user launches a VDI client, that client (guest OS/desktop) is assembled using a layer cake approach to build a functioning desktop in many VDI software offerings. That process is very storage intensive with a massive number of I/Os. Here, a SAN built on SSDs can offer a significant performance boost.
More on VDI storage
Guide to VDI storage management
How IOPS influence VDI storage performance
How VDI performance monitoring differs from virtual servers
Another storage intensive process is virtual machine booting, where disk I/O is used to load the virtual OS. Once again, the move to SSDs can significantly increase performance. Additionally, those same SSDs will bring a performance boost to other IT processes, helping to improve the overall ROI of your environment.
SSDs now come in all shapes and sizes -- with some designed for large disk arrays, others used as a first level cache for SANs and some deployed in network-attached storage or even local endpoints. It all comes down to placing SSDs where they offer the biggest benefit for the most users -- which usually means placing SSD-powered SANs into the environment.
Performance, reliability and the growing need for capacity are all catalysts for SSD adoption, allowing IT to share the costs of SSD across multiple business units, departments and services. Ease of deployment, reliability and capacity improvements can all be used to justify the higher expense of SSDs.