Direct-attached storage (DAS) is computer data storage that is connected directly to the computer accessing it, such as a PC or server, as opposed to storage that is accessed over a computer network, such as network-attached storage. For individual computer users, DAS comes in the form of a hard drive or solid-state drive. DAS can be deployed inside a server chassis or as an external storage enclosure directly connected to a card plugged into the internal bus of a server. The term “direct-attached storage” is a retronym for storage area network and network-attached storage.
Pros of direct-attached storage
- Low cost: Since the only DAS costs are the storage device itself and any drive enclosure, it’s cost effective compared to storage solutions that require hardware and software to run and manage the devices.
- High performance: Because DAS is attached to the computer that requires the data, access to it is fast. Network connectivity and congestion issues do not directly affect DAS.
- Easy setup and configuration: Computer systems supplied with internal DAS are ready for immediate use. External network storage can be used as soon as it’s plugged into a port such as a USB port.
Cons of direct-attached storage
Direct-attached storage does have its challenges though. They include:
- No central management and backup: While it’s not a problem for individuals or only a few computers using DAS, growing organizations may run into problems ensuring that the data stored on DAS is available and backed up. It becomes more complicated and costly than arranging redundancy and backups on networked storage devices.
- Poor performance possibility: DAS connected to a PC can be slow to share data with other computers on a network. This is due to performance depending on the resources of the host PC. However, the issue is less prevalent when DAS is connected to powerful servers dedicated to storage.
- Limited scalability: Unlike software-defined storage that has unlimited storage, DAS is difficult to scale because the number of internal drive bays, availability of external ports, and capacity of external DAS is limited. If internal DAS needs to be upgraded, the host computer may need to be shut down during the upgrade.