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How to evaluate VDI storage requirements

There are a variety of factors that affect VDI storage, including system requirements and supported workloads. Evaluate these two factors to ease the VDI planning process.

IT must take a variety of factors into account during the VDI planning process, and storage is one of the most crucial components.

Here, we'll delve into how system requirements and supported workloads can affect VDI storage planning.

System requirements

The system requirements for VDI storage depend on how IT implements the VDI components and desktops. For example, most VDI vendors support both persistent and nonpersistent desktops. Persistent desktops maintain user data and settings from one session to the next; nonpersistent desktops do not. As a result, persistent desktops require more storage capacity for both the primary data and backups.

IT should review the individual features available in VDI products to determine how they affect VDI storage requirements. For example, VMware offers vSAN, a software-defined storage platform integrated into vSphere. VSAN virtualizes the local physical storage in a vSphere cluster to create a distributed shared storage product that can simplify management and help reduce storage costs.

VMware also offers View Storage Accelerator to reduce IOPS requirements, View SEsparse disk to reclaim storage capacity and Virtual Volumes to better control storage-related operations. In addition, VMware supports desktop cloning, which enables administrators to create full or linked desktop clones from a master image. Cloning can reduce overall capacity needs, but it can also lead to write amplification issues and increase I/O requirements, especially with persistent desktops.

Most vendors offer features that can affect VDI storage requirements and the overall VDI, usually with the intent of improving performance and resource utilization. Citrix, for example, provides Machine Creation Services and Provisioning Services, both of which can help deliver better performance and reduce storage requirements for each VM.

IT should also evaluate the VDI storage requirements for implementing the product's components, as well as the storage resources necessary to support backups, site-to-site replication and disaster recovery operations.

For example, when planning a Citrix implementation, IT needs to estimate Microsoft SQL Server database requirements and take into account the database and transaction log files for the three primary databases -- monitoring, site configuration and configuration logging -- as well as the temporary database (tempdb). IT also needs to provide storage to back up those databases and ensure their continuous availability.

Supported workloads

The final piece of the storage puzzle is perhaps the most important: understanding the workloads that the VDI must be able to support. IT should evaluate the types of users connecting to desktops, how and when those users work, and anything else about their behavior that can inform storage planning. For example, productivity workers generally have lower IOPS requirements than knowledge workers, who require higher-performing systems and resource-intensive applications.

As part of their calculations, IT teams should determine the number of users and number of desktops they require, which are not necessarily the same. Teams should also determine how much user data they will store, which guest OSes will run, the types of applications users will require and any other special performance or storage requirements for them to carry out day-to-day operations.

In addition, the calculations should include both existing and future needs, accounting for factors such as expected growth and the influx of temporary workers. IT should also account for anticipated boot and login storms or other situations that can result in high I/O demands.

Part one of this two-part series discusses how storage technologies can affect VDI storage planning.

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