Are solid-state drives the best VM storage option for high performance?
Let me begin by defining some terms. In this case, we're talking about storage performance not processing performance, and storage performance is generally defined as IOPS. And for the purpose of this discussion, we're going to ignore channel throughput, with respect to its performance.
In general, solid-state drives (SSDs) do offer the best storage performance regardless of whether it's a virtual or physical environment, if it's IOPS that are needed. The challenge is where those IOPS should be used. If it's a physical machine where you're dealing with different virtual machine (VM) workloads, from the storage array's perspective, the IOPS or read/write requests appear to be random because the workloads of those machines are different. Those machines are accessing different parts of the disk, and it's hard for the automated tiering storage software to get a good handle on where those IOPS are going to be coming from or where requests are going to be coming from, and therefore it's difficult to predict. If you're in that case, you're probably better off putting the SSD into the server itself, where it's going to be managed by the server and you're generally going to get better performance.
In contrast, if the VMs are serving similar workloads -- let's suppose a virtual desktop environment where you have multiple VMs serving multiple users, but they're all VDI machines -- then the IOPS going to the array will look very similar. So you get a lot of benefits from having that Tier 0 SSD on the array itself, where you can significantly reduce the back-end hard disk reads and get much better VM storage performance.
About the author: Phil Goodwin is a storage consultant and frequent TechTarget contributor.
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