NAS Buyer's Guide: Feature considerations for SMB

Small to medium-sized business-oriented NAS appliances have become more feature-rich over the last several years. Below are some key features to look for when purchasing a NAS for small business.

Solid-state drive support: NAS vendors may support SSDs in several ways. The appliance can use SSDs for normal data storage or for caching. Some vendors design their NAS appliance primarily for hard disk drives, but include a drive bay specifically designed to accommodate an SSD for caching purposes. The appliance automatically transfers hot data to the SSD so it can be read as quickly as possible. Some vendors also use part of the SSD storage for caching write operations.

Flexible storage support: When contemplating a NAS for small business, make sure the appliance is able to grow with you. This means you should be able to use whatever drives you want, assuming they are physically able to connect to the appliance's storage controller. If, for example, you decide to upgrade to larger drives or make the switch to SSD storage, the appliance should let you do so.

Alerting mechanism: NAS appliances generally provide storage redundancyto prevent data loss in the event of a disk failure. Even so, you need a way to gauge the status of the disks within your NAS appliance.

Vendors take a variety of approaches to reporting on disk health. It's best to look for a product that conveys its health status through colored lights, email messages or an integrated display. While Web consoles generally work well, the storage administrator has to remember to periodically log into the console. Alerting mechanisms that do not require administrative effort tend to do a better job.

Supported protocols: Most NAS appliances geared toward the small business market support the Common Internet File System and Server Message Block (SMB). Some also support the Apple Filing Protocol and a few even support iSCSI block storage.

If your NAS for small business purchase does not include a backup battery, you should make sure to budget for an uninterruptible power supply.

You should determine which protocols your appliance will need to support before you start shopping. If you need an appliance that supports SMB, key Windows Server features such as Hyper-V Virtual Machine Storage are onlysupported on SMB 3.0.

Thin provisioning: Depending on how you plan to use the NAS appliance, thin provisioning may or may not be an important feature to have. If you plan to configure a NAS appliance as a file server, it probably isn't necessary to thin provision. If you plan to create a number of different volumes on the appliance, thin provisioning can be helpful.

Thin provisioning allows a volume to consume storage space only as it is needed. For example, you create a 40 GB volume that is thinly provisioned. Although the operating system treats this volume as a bona fide 40 GB volume, the volume will initially consume less than 1 GB of physical disk space. Additional storage space is only consumed when data is written to the volume. The advantage to thin provisioning volumes is that it allows you to create volumes that are large enough to accommodate future data growth without consuming physical storage unnecessarily.

Support for mixed drive sizes: It may be easy to initially dismiss this feature as being unimportant, but there is at least one reason why your NAS for small business purchase needs to support the use of mixed disks.

Imagine for a moment that you purchase a NAS appliance and install a 1 TB disk into each of the drive bays. You also decide that you need protection against physical disk failure, so you configure the appliance as a RAID 5 array. A few years later, one of the disks in the appliance fails. You get ready to replace the disk only to discover that vendors no longer sell 1 TB drives. If your NAS appliance does not allow you to mix disk sizes, you will have to figure out a way to offload all the data from the appliance before another disk fails and then incur the expense of replacing every disk in the appliance with whatever disk size is now available. Moral of the story: Purchasing an appliance that supports mixed disk sizes now can potentially save you a lot of money and frustration later on.

Flexible data protection: All administrators seem to have their own ideas about how to configure storage. Some attempt to achieve the best performance, while others use a configuration that will provide the best protection for their data. Still others use a storage configuration that falls somewhere in the middle. You should ensure your NAS appliance offers a high degree of flexibility with regard to the storage architectures it supports.

Some lower-end NAS appliances only support mirroring. Others support RAID 1 and RAID 5, but nothing else. A good NAS appliance should give you the freedom to choose your own storage architecture. The better NAS appliances support RAID 0, RAID 1, three-way mirroring, RAID 5, RAID 6 and RAID 10. Some provide the option of designating a disk as a hot spare that can take over in the event of a disk failure. The number of drive bays in the appliance plays a major role in the storage architectures supported.

Built-in battery backup: An unexpected power loss can cause the data in your NAS appliance to become corrupted. The risk increases if data is striped across multiple disks. Some vendors build a backup battery into their appliances as a way of preventing data loss during power outages. If your NAS for small business purchase does not include a backup battery, you should make sure to budget for an uninterruptible power supply.

As you can see, there are a number of features that must be considered when shopping for a NAS appliance for a small business environment. There are also major differences between the various NAS vendor offerings, so it is important to take the time to choose an appliance that will meet your needs.