Areca

These NAS units are the largest around, offering five HDD bays at a minimum and ten or more in many cases. They are typically geared towards advanced users who need plenty of storage space, and many are supplied in rackmount cases for use in industry and large-scale businesses. These units are not sold with hard disks so you'll need to add your own – it's best to get matching models and capacities, especially if you plan on using RAID.

If need more info to help you choose the right NAS, or you can't see the exact specification you'd like custom built NAS please click here.

Direct Attached Storage or DAS is an external storage device that is connected directly to a server or workstation without a network device in between (ie there is no hub, switch or router required) using USB, Firewire or eSATA for example. This direct connection ensures fast access to data. A DAS will work as though the hard drives are internally connected, meaning drives can be partitioned, formatted and set up like any other internal hard drive or raid array. These DAS devices are available for standalone desk or rack mounting.
Updated

External hard disks are ideal for backup or portable file storage, and these drives come in a large range of categories: some use desktop-sized 3.5in hard disks, other use smaller 2.5in drives, and faster products use SSDs. Most drives use USB 3, Thunderbolt or eSATA connections, and these drives can come in different types of case – some are designed to be tiny, and others are ruggedized to stand up to dust, water and even fire.

These cards can be installed inside desktop PCs to provide professional-level storage capabilities. They use the increased speed offered by the PCI Express bus in order to facilitate super-fast RAID configurations, and the cards in this category include between 12 and 32 ports - perfect for the most demanding of corporate setups.

The controller cards in this category provide storage speeds far in advance of the standard SATA ports inside desktop PCs and office workstations. These products are mid-range components with four connectors.

These controller cards are entry-level models that use a 1x PCI-E slot in order to provide faster SATA performance that any standard storage connector can provide. The products in this category have two connections for small-scale RAID arrays, and some work in Macs as well as PCs.