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Storage is one of the most important aspects when planning virtual desktop infrastructure. Thus, IT must account for a range of VDI storage considerations to ensure that it can support all workloads.
IT should think of VDI storage in terms of three broad categories: storage technologies, system requirements and supported workloads. Here, we'll delve into how storage technologies affect VDI planning.
Choosing a storage product
Storage technology includes everything from drive types to storage configurations to transport protocols. For example, when planning storage, IT can choose hard disk drives (HDDs), solid-state drives (SSDs) or hybrid systems that combine the two.
HDDs were once used almost exclusively for VDI, but SSDs are quickly becoming the drives of choice because they significantly outperform HDDs. In addition, SSD densities have been steadily increasing as prices decrease, making the all-flash array a more viable option than ever. In some situations, however, hybrid storage can adequately support VDI workloads and bring prices down even more.
IT must ensure that storage drives can deliver the required IOPS to support the expected VDI workloads, which are typically random and fluctuate depending on the time of day, number of users and the supported applications. Different types of drives provide different levels of IOPS, and even drives of the same type can vary substantially when it comes to performance. For example, SSDs generally deliver much higher IOPS than HDDs, but not all SSDs are created equally. IT must evaluate SSDs carefully to ensure that they can meet the expected demand.
Other VDI storage considerations can also affect performance. For instance, server-side caching can reduce I/O latency. IT can select RAID levels to match workloads and use tiering to improve response times for virtual desktop components that need to load more quickly. The effectiveness of the array management software can also make a difference when it comes to maximizing I/O. In addition, some technologies such as deduplication or thin provisioning can improve resource utilization, but they can also potentially affect performance.
Deployment and configuration considerations
Another important VDI storage factor is how IT configures or deploys the storage. IT must determine whether to use direct-attached storage (DAS), network-attached storage (NAS) or a storage area network (SAN). DAS might be cheaper, but NAS and SAN can usually better support large-scale operations, with SAN offering more availability and reliability.
Hyper-converged infrastructure (HCI) uses DAS to provide pooled storage resources, which has proven an effective strategy for VDI workloads. IT teams should evaluate each option to understand how it affects their particular circumstances.
Storage interfaces and protocols can also affect VDI performance. Common interfaces include Serial Advanced Technology Attachment (SATA), Serial-Attached SCSI, Fibre Channel and Peripheral Component Interconnect Express. Common protocols include the Small Computer System Interface (SCSI), Internet SCSI, Advanced Host Controller Interface (AHCI), non-volatile memory express (NVMe) and NVMe over fabrics.
When IT combines the interface with the optimal protocol, it can make a significant difference in throughput and performance. The network fabric that supports communications, such as Ethernet or InfiniBand, can also affect throughput and performance. For example, Fibre Channel interfaces perform better than SATA interfaces, and the NVMe protocol is faster than AHCI.
The technologies around interfaces, protocols and network fabrics are changing rapidly, and IT teams must carefully evaluate the available options before making a choice.
Part two of this two-part series discusses how system requirements and supported workloads can affect VDI storage planning.