So what should SMBs be on the lookout for when shopping for a NAS? We've put together a list of the most desirable features below, grouped into several broad categories. You may not need everything mentioned, though it is hoped that this will help you arrive at a decision about the right NAS for your organization.
When buying a new NAS systems, the first question will obviously be centered on the projected storage capacity that will be required, which is closely related to the number of supported hard disk drives (HDD). Note that some NAS options may be upgradable with an expansion chassis for additional drive bays. Also, be on the lookout for support of external storage devices using USB or eSATA ports, which may be useful as a temporary capacity fix, or for the purpose of performing a backup. (See "Data Backup and Synchronization" below.)
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Do remember to ensure that the NAS is capable of supporting the largest capacity HDD currently available, which would be 3TB for a 3.5-inch SATA HDD at the time of writing. Some NAS appliances are compatible with both 3.5-inch and 2.5-inch form factors, though the latter may be of limited utility unless there are plans to deploy solid state drives (SSD). HDD should also be hot swappable for maximum flexibility, though today only the most basic models NAS do not support this feature.
In terms of network connectivity, the common denominator at the moment appears to be gigabit Ethernet, though dual gigabit Ethernet ports are increasingly common in mid-range NAS models. However, do not assume that link aggregation is automatic with units with dual Ethernet ports, as some work only in fail-over mode. Some NAS may also be upgradable to 10G Ethernet with an add-on card, which may be an important consideration if there are plans eventually to upgrade the core network to 10G networking.
It is also important for businesses to consider whether the NAS comes with a redundant power supply unit (PSU). Failure of individual drives aside, the PSU is the hardware component most likely to experience a critical failure, and depending on the immediate availability of spare parts, that failure can result in a lengthy downtime.
Hard disk performance
Transfer speed over the network is the primary performance indicator of a NAS. This transfer speed is typically measured when uploading or downloading large files from the appliance using a file-level protocol, and where applicable, at the block level as well. The importance of each will of course depend on the anticipated usage of the NASÂa better file access speed is key for businesses looking to deploy the NAS as a storage repository for users, while a good block access speed is of interest to outfits intending to deploy it with servers.
Some high-end NAS may support auto-tiering with SSD for enhanced performance, though the exact performance boast here is not easily evaluated. Given that most mid-level NAS systems sold today are already capable of saturating a gigabit connection, it is advisable to avoid placing undue emphasis on absolute performance figures. Unless the performance is particularly bad, businesses should evaluate the performance traits of a particular NAS together with its overall capabilities.