Unified storage systems are getting a lot of attention lately. These systems provide both block and file services across multiple protocols via a single storage system. They are an ideal option for data centers looking to simplify their storage infrastructure by centralizing all the demands of the data center onto a single storage system.

Every major storage vendor has a unified storage system of one kind or another and almost every startup we speak with is claiming to have a unified system. In fact, we are tracking over 35 startups that claim to have a unified storage system. Over the next several columns I'll provide some tips to sort through the maze of options available to you.

In this column we'll look at the confusion some vendors create when they claim that another vendor's storage system is really unified. As is always the case in technology and especially in storage, a single definition of a term can be hard to come by and that is true of unified storage systems.

[ Read about another "big" storage question: Storage's 'Big' Overkill: Truth About The Trend. ]

The truth is you are not really buying a unified system just to have a unified storage system. You are trying to find a storage system that will solve your capacity and performance problems while reducing system administration time. If the vendor that best meets your current needs isn't truly unified--but solves your problem at a price you can afford, then go with them.

What Is A Unified Storage System?
The word "unified" implies that a system supports multiple connectivity and access options. For most systems, it means that the unit can serve files (NAS) and blocks (SAN) from the same device. For others, it means that the system can only do block but you can connect via iSCSI or fibre. In the purest sense, a unified system should be able to provide block access across all the available connectivity options (fibre, iSCSI, FCoE, etc.) while at the same time providing file access across NFS and SMB.

What is really important is what your data center needs. Do you need high-performance NAS? If you are just serving up home directories to a small group of users, then probably not. But if you are also going to use NAS to store your virtual machine images, then the answer can quickly change to yes. If you can use fibre or iSCSI with either a file server or virtual NAS connected to the storage system, then you might not need a unified system at all.

Another challenge is that most unified systems tend to be better at one capability than the other. This means they are a NAS that figured out a way to provide block storage, or they are block storage with some sort of NAS function integrated. Although most environments will use a mixture of workloads, a particular workload will often be the most important. Make sure that you test the specific conditions and configurations that will be most important to you.

Keep Your Options Open
Unified storage systems are about options. Having options means you don't have to make the perfect choice now, nor do you have to predict future needs. You do need to know what is most important to your current situation from both an access and protocol perspective. You also want to make sure that the other components of the unified solution are acceptable to meet the lower-priority needs.

In our next column we will discuss some of the key features to look for in a unified storage system, such as SSD integration, mixed workload support, VMware integration, scalability, and efficiency. Then we will wrap up the series with a discussion on whether you should build your own unified system or buy a turnkey system.

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