DAS is the abbreviated form for “direct-attached storage,” which is basically digital storage that is directly attached to the system which accesses it, unlike the storage which is normally accessed over the network of the computer system. Thus we can say that, DAS is a dedicated digital storage device which is attached directly to a PC or a server through a cable. Direct-attached storage is vitally straightforward, simple and clear-cut, which is why; DAS devices and systems are not becoming increasingly used due to the growing demands for effective IT storage solutions.
- For any individual PC user, the system’s hard disk drive is basically the most common form of DAS, i.e. the direct-attached storage.
- In enterprises, however, the separate disk drives in one single server are DAS, same as the groups of drives, which are external to that server, but are attached directly either through SCSI/SATA/SAS interfaces.
- Hard drives
- Optical drives
- External storage drives
Key Protocols That Are Generally Used for DAS Connections
- Fibre Channel
- SAS or the Serial Attached SCSI
- SCSI or the Small Computer System Interface
- ATA or the Advanced Technology Attachment
- SATA or the Serial Advanced Technology Attachment
DAS, SAN and NAS
- Main alternatives to DAS are NAS (network-attached storage) and SAN (storage area network).
- Major difference between DAS and NAS is that unlike NAS, a DAS device is directly connected to the server without the need of any network connection. However, most of the modern day functions of storage are not depending on whether that storage is done directly (using DAS), or through a network (using SAN/NAS).
- Another major difference between DAS and NAS is that unlike NAS storage, in the DAS storage system, it is only accessible directly from the host machine to which that DAS storage has been attached.
- In the DAS storage, none of the network hardware or any related operating environments are incorporated for providing a facility of sharing the storage resources separately and independently.
- DAS storage to a connected host machine can definitely be shared by that particular host machine.
- SAN is more similar to DAS than NAS, with the major dissimilarity being that – DAS is a one-to-one sort of relationship between the host and the storage, but SAN is a kind of many-to-many relationship between the host system and the storage.
- In the DAS storage system, data islands are created, as the data is not allowed to be shared with other different servers.
- A typical direct-attached storage device can be either an internal one or an external HDD.
- As per the data criticality, the disk drives can be protected with different RAID levels.
- Modern day DAS systems consist of unified disk array controllers that have very advanced functionalities
- Normally, in a DAS system, there is a data storage device, which has some enclosures that hold multiple hard disk drives, which are directly connected to a machine through a HBA (host bus adapter). Now, between these 2 points, there exists no such network device (like a hub or a switch or a router), and this is the prime characteristic of the direct-attached storage system.
Advantages & Disadvantages of Using DAS Systems
- Larger availability
- Greater data security
- Increased fault tolerance
- Expanded storage capacity
- Zeroed network setup complications
- High rate of access due to absence of SAN
- Lofty administrative costs
- Only 1 user is allowed at one time
- Data cannot be accessed by different user groups
Reasons of Corruption
- Virus attack
- Partition loss
- Improper removal of DAS
- OS crashes
- Damage of DAS
How to get rid of the problem of Corruption?
There is an easy solution available which helps to get out of the problem i.e. DAS Data Recovery Software. It is one of the easiest ways to get all the lost and accidentally deleted data from DAS. The software supports to recover data from all the DAS i.e. hard drives, MMC cards, SD cards, pen drives etc.