Direct Attached Storage (DAS)

What Is Direct Attached Storage (DAS)

Direct-attached storage (DAS) is a type of digital storage system that connects directly to a computer, workstation, or server without going through a network. Since DAS is linked only to a single device, it is not accessible to other systems unless they connect through the host machine. DAS can be either internal or external and includes storage devices like hard drives, solid-state drives (SSDs), optical media (e.g., CDs, DVDs), and tape storage. DAS is commonly used for local data storage where fast access to files on a single device is needed.

What is DAS used for?

Direct-attached storage (DAS) is primarily used for providing internal or external storage to individual computers and servers. Internally, it takes the form of hard disk drives (HDDs) or solid-state drives (SSDs) directly connected to the motherboard, while externally, devices like USB drives and external hard drives are also considered DAS.

DAS is commonly used in small and medium-sized businesses (SMBs) as file servers, offering dedicated storage for specific workstations or servers. It is also used in data centers where dedicated storage is needed for specific applications or servers. Larger enterprises may integrate DAS with networked storage systems like Storage Area Networks (SAN) or Network Attached Storage (NAS) to enhance performance and capacity.

DAS is often chosen for situations requiring high performance and large storage capacities, making it ideal for SMBs that need simple, cost-effective storage without the need for data sharing across an organization. Additionally, external DAS solutions can be expanded at a lower cost compared to more complex options like SAN and NAS.

Why is it called DAS?

The term "DAS" stands for Direct-attached storage, which is named as such because it is directly linked to the computer or server. This implies that the storage is accessible solely by the device it is physically connected to and not accessible over a network. A DAS setup can consist of hard disk drives or SSDs housed within a computer or server chassis, or an external storage enclosure connected directly to a server.

DAS can also refer to collections of external drives that are directly attached to a server using interfaces like SATA (Serial Advanced Technology Attachment), SCSI (Small Computer System Interface), SAS (Serial-Attached SCSI), or FC (Fibre Channel).

Unlike network-attached storage solutions, DAS does not utilize Ethernet, Fibre Channel connections, or network devices such as hubs, switches, or routers to provide storage access.

How does DAS work?

DAS can be either internal or external and does not rely on a network connection to link to the host computer or server. Internal DAS typically involves a storage device connected internally to a server or personal computer using a high-speed host bus adapter (HBA).

Every personal computer is equipped with at least one internal DAS drive, which can be a traditional HDD or a faster SSD connected via a SATA interface. Similarly, servers feature internal storage that can be linked using interfaces like SATA, SCSI, or SAS.

External DAS examples encompass external hard drives and drive enclosures capable of housing multiple drives. These are linked to servers and workstations using connection interfaces such as USB, eSATA, SAS, or SCSI.

The computer to which DAS is connected manages and controls the DAS. Networked computers require communication with the computer hosting the DAS to access data, rather than accessing the data directly.

Why Use a DAS for Storage?

Direct-attached storage (DAS) offers several compelling advantages for users seeking efficient and cost-effective storage solutions:

• High Performance: DAS provides rapid data access because it connects directly to the computer or server that needs the data. This direct connection minimizes latency, ensuring quick read and write operations. Unlike network-attached storage (NAS) or storage area networks (SAN), DAS is not affected by network congestion or connectivity issues, resulting in consistently high performance.

• Easy Setup: Setting up and configuring DAS is straightforward. Internal DAS, such as hard disk drives (HDDs) or solid-state drives (SSDs) installed in a computer or server, is typically ready for use immediately after installation. External DAS devices, such as USB drives or external hard drives, are designed for “plug and play,” allowing users to connect them through a USB port and start using them right away without complex setup procedures.

• Low Cost: DAS is a cost-effective storage solution compared to NAS and SAN systems, which involve additional hardware and software for managing and operating the storage infrastructure. With DAS, users only need to invest in the disk drives and drive enclosures they require, avoiding the higher costs associated with networked storage solutions.

In summary, DAS is a practical choice for users who prioritize performance, simplicity, and cost-efficiency in their storage setup.

When to Use Direct-Attached Storage (DAS)

There are specific scenarios where Direct-Attached Storage (DAS) might be the preferred choice:

• Budget Constraints: DAS presents a more economical option compared to alternative network storage solutions such as SAN or NAS, which can incur significant costs ranging from hundreds to millions of dollars. For small and medium-sized businesses requiring ample storage but constrained by budgetary concerns, DAS serves as a cost-effective storage solution. Setting up a DAS system entails acquiring the necessary storage devices and, if needed, optional enclosures. Additional storage can be procured and integrated easily as needed.

• Simple Storage Solution: DAS proves advantageous for entities lacking extensive network infrastructures or those not necessitating widespread data sharing within the organization. For such businesses, DAS offers a straightforward storage remedy that is uncomplicated to implement and demands minimal IT support.

In essence, DAS serves as a practical solution for businesses facing budgetary constraints or those looking for a straightforward and cost-effective storage option without the complexity of elaborate network configurations or extensive data sharing requirements.