Like you, I’ve been excited to see solid
state drives (SSDs) come down in price and options increase on how to use the
high performance storage resource. How to best utilize SSDs is a question many
of us are facing, and the technology is moving very fast. A lot of data center
administrators and decision makers have had excellent performance gains when
using SSDs on end-user computing devices. But when it comes to increasing the
storage performance in the data center, the process gets much more involved.
One option is to leverage the hypervisor,
with the new vSphere Flash Read Cache feature that comes with vSphere
5.5. Looking deeper into the VMware offering, the upcoming VSAN feature may
also be an option. Much like the Flash Read Cache, VSAN introduces a caching solution (which is not a tiering solution by
itself) across nodes to provide a logical storage volume from local storage
systems. VSAN requires some amount of SSD in place and functions as a shared
storage disk system for VMware VMs. Categorically, VSAN is a hyper-converged
infrastructure technology that is combining compute (CPU/Memory) of servers
with the role of shared storage (logically pooled). On the Hyper-V side,
Windows Server 2012 R2 introduces a tiering solution with Storage Spaces.
Aside from the VMware offering, a slew of
storage systems leverage SSDs today. Many of these storage systems have a mix
of SSDs and traditional rotating storage, with varying levels of features and
sophistication that will increase workload performance by leveraging SSDs where
needed. It is important to note how these specific implementations differ, as comparisons
among them are confusing. I’ve not gone through the duty of naming the players
in this space because each has its own strengths that differentiate it from the
others. Data center administrators just need to see performance improvements
with economics that fit.
There are a few things we should know not to
do. For example, don’t simply put SSDs in blindly. For one thing, there are a
number of decision points among SSD types. There are consumer- and
enterprise-class SSDs, and of course the data center implementation should be
more in line with the enterprise-class models. Also consider disk controller
systems. While they may support SSDs from a bus and interface standpoint, they
may not use the disks intelligently. This can lead to uneven wear and accelerated
failure as well as a wasted investment if the performance isn’t utilized
The SSD roadmap
So what’s one to do? Here is the thought
process I would go through. The first step is to identify what will benefit
from the SSDs. My natural choice today is the virtual infrastructure. Having a
high performance disk tier available to VMs makes this decision easy due to the
consolidated and portable nature of VMware and Hyper-V environments.
The next topic I’d tackle is whether I want a
native hypervisor solution providing the SSD benefits or a storage system. This
is a big change in terms of host configuration and possibly storage system
cost. It would be a relatively straightforward process to change all hosts to
have an enterprise-class SSD and leverage technologies like VSAN or vSphere
Flash Read Cache. If the storage system route is chosen, that could be a larger
investment but may introduce true tiering vs. only caching.
From there, I’d see what difference the various
options make on the workloads that give me the most grief. We have to try these
new technologies before we make a significant investment in our practice.
That is the recommendation today. It’s very
possible that in a few months or years, the landscape will materially change
(again). How are you addressing the influx of SSDs in your data center? What
are you trying to accomplish or avoid? Share your comments below.