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Compare XtremIO vs. Unity all-flash storage system for VDI

Dell EMC offers two all-flash storage options geared toward VDI shops. One suits companies with fewer than 500 persistent machines, and the other is for larger deployments.

One of the best reasons to consider an all-flash storage system is to support a virtual desktop infrastructure deployment. VDI requires fast storage, and a lot of it.

Dell sells two all-flash storage platforms that target VDI workloads: Dell EMC Unity and Dell EMC XtremIO X2. Unity is a midrange storage platform for small to medium-sized businesses, and XtremIO is an enterprise-scale platform for organizations with large VDI deployments.

Unity all-flash storage system

In May 2016, EMC introduced the Unity platform to replace its aging VNX systems. Several months later, Dell acquired EMC, and it has since expanded the Unity product line by adding four additional all-flash platforms: Unity 350F, 450F, 550F and 650F. These arrays are faster and more efficient, and they support larger capacities than either the VNX systems or the earlier Unity models.

Dell offers Unity in several forms. The first is the purpose-built physical platform, which you can configure with all-flash drives, or in a hybrid setup that includes a combination of flash and traditional hard disks. An all-flash storage system delivers the best performance because it offers higher I/O rates and submillisecond response times.

The second form is the Unity Virtual Storage Appliance (UnityVSA), a software-defined storage product for consolidating hardware resources. You can download and use the UnityVSA Community Edition for free, or you can go with the subscription-based Professional Edition, which includes technical support and can handle larger capacities. Both editions require that you install UnityVSA on a VMware ESXi host.

Unity also comes as part of a Dell EMC VxBlock System 350 or Vblock System 350 converged infrastructure. With this option, you can take advantage of the Unity all-flash storage system and get a package that simplifies your VDI implementation.

The Unity platform primarily targets VDI implementations with fewer than 500 virtual desktops, but you might be able to support up to 2,000 nonpersistent desktops -- as long as your VDI deployment stays nonpersistent. Persistent virtual desktops require significantly more storage.

An all-flash storage system delivers the best performance because it offers higher I/O rates and submillisecond response times.

Unity is based on a modern 2U form factor, which eliminates the need for the type of special hardware or software often required to support block or file storage. A single Linux-based operating environment controls the entire system, which makes it possible to deliver a unified storage system that supports up to 80 SSDs in a three-rack unit enclosure, with 500 TB of effective capacity per rack.

In addition to block and file storage, the Unity platform also supports VMware Virtual Volumes, and it provides concurrent support for the NAS, SCSI and Fibre Channel protocols. Each system includes dual storage processors based on Intel Broadwell microprocessors, with core counts ranging from six to 12.

Unity also comes with the software you need to implement and manage the all-flash arrays; it includes the Unisphere Management Suite, an HTML5 application that simplifies administration. Plus, Unity provides access to the CloudIQ service, which offers a portal for monitoring Unity arrays. The platform also supports inline compression, encryption and native data protection. It does not, however, provide deduplication services.

XtremIO all-flash storage system

XtremIO is an established, purpose-built enterprise storage platform. With XtremIO X2 -- Dell's first major update to the system in several years -- you can scale both up and out to support more than 10,000 virtual desktops.

The XtremIO platform is based on a multicontroller, N-way active model, in which the storage array scales to the number of available controllers (eight, as of this writing). During normal operations, all controllers share the I/O load. But if a controller fails, the remaining controllers take over: The arrays can deliver consistent and predictable performance with submillisecond latencies.

XtremIO also uses content-aware, in-memory metadata to optimize flash operations. This metadata intelligence enables compression, deduplication and integrated copy data management, making it possible to consolidate diverse tier 1 workloads.

At the heart of the XtremIO platform is X-Brick, a storage building block that consists of two active-active controller nodes that eliminate any single point of failure. You can scale each X-Brick up to 138 TB of raw storage, and you can scale a cluster out to eight X-Bricks to deliver up to 1.1 petabytes (PB) of raw storage. Factor in deduplication and compression, and you end up with 5.5 PB of effective capacity.

Another performance boost comes from the use of nonvolatile random-access memory (NVRAM), which can reduce application latency, as well as improve IOPS performance and copy operations. NVRAM also helps minimize write operations and improve drive reliability.

XtremIO X2 also comes with XIOS 6.0, a software package that includes optimization technologies and an updated version of XtremIO Management Server. It also includes advanced analytics and reporting capabilities, as well as global search functionality.

You should have no trouble choosing between Unity and XtremIO: Base your selection on the number of desktops in your VDI deployment. If you're working at the 500 desktop threshold, consider future VDI storage needs, as well as your present needs. And you should compare Dell's storage platforms to others on the market to be certain you choose the right all-flash storage system for your VDI needs. 

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