External or internal storage media such as HDDs, SSDs, flash drives, etc. are used by everyone for data storage, data transfer and data backup. Although these devices differ from each other, they have one common feature – they are connected directly to a computer. For this reason, these storage devices are also referred to as Direct Attached Storage or DAS.
A DAS is a type of storage device that is mainly used by private individuals and small and medium-sized businesses (SMBs). It makes storing or accessing data easy and fast. As these devices are connected directly to a single system or workstation, the data on them is easy to access offline.
Let’s delve deeper to find out more about this storage unit in detail.
What is THAT?
As mentioned above, Direct Attached Storage (DAS) is an isolated type of storage media that connects directly to a single computer or workstation. There are various forms of Direct Attached Storage that are commonly used. Some common examples of DAS media are –
- Hard disc drives (HDDs)
- Solid state drives (SSDs)
- Flash drives
- Optical media
- USB housing, etc.
DAS is normally used in PCs or servers as an internal drive. It is also used as an external drive like an HDD or an SSD to create backup copies of your data. Small and medium-sized companies also use DAS in the form of file servers and private storage connected to dedicated servers.
How is DAS accessed?
A direct-attached storage device is connected to a host computer, private server or workstation via an interface. The setup is very easy to understand – a DAS media is connected directly to a computer/workstation via an HBA or host bus adapter and does not use hubs, switches or routers. External DAS media are connected via cables.
Some of the most commonly used interfaces are –
- ATA or Advanced Technology Attachment
- SATA or Serial Advanced Technology Attachment / eSATA
- SCSI or Small Computer System Interface
- SAS or Serial Attached SCSI
- FC or fibre channel
- IEEE 1394 also known as Apple FireWire
- NVMe
- USB or Universal Serial Bus
Why is DAS used?
A DAS medium is mainly used for creating offline and private data backups. Since DAS is not part of an active network, it is also used as a high-performance storage device, as it avoids unnecessary server traversals and latency issues that occur with networked storage solutions such as NAS, cloud storage, etc.
Individuals use various forms of DAS media, such as HDDs, SSDs, flash drives, SD cards, etc.. However, for an individual such as a graphic designer, video editor or app developer, a single drive is not sufficient. In this case, a USB enclosure with a combination of SSDs/HDDs in a RAID configuration is used.
This type of DAS setup is not only efficient, but also offers the possibility to expand the storage in the future. This makes DAS an extremely flexible and customizable storage type.
Advantages and disadvantages of DAS
Like every technology, DAS also has its advantages and disadvantages. These are listed in a table below –
| Advantages | Disadvantages |
| Connects directly to a computer | Limited scalability |
| Offers high data transfer rates | Inconvenient, as additional drives are required |
| Cheaper than SAN or NAS | Limits the sharing of data on multiple computers |
| Easy to configure, install and manage | High risk of data loss due to hard disc errors or hardware problems. |
What to do in the event of data loss from DAS?
Regardless of the type of DAS medium used, it is susceptible to data loss. The main reasons for data loss on a DAS are
- Hard disc error
- Accidental deletion
- Formatting
- Defective cable/HBA
- Malfunction of the drive housing
With a DAS configured as a RAID, additional redundancy prevents data loss. However, redundancy depends on the RAID configuration selected, i.e. RAID 5 (failure of 1 drive), RAID 6 (failure of 2 drives), etc. If the hard drive failure is greater than the predefined values, the setup will fail, resulting in permanent data loss.
Data loss is unprecedented and DAS media is no exception. DAS media is prone to data loss for various reasons as described above. However, most cases of data loss, such as accidental deletion, formatting, etc., are easy to fix with RAID data recovery software.
Regardless of which DAS you use, advanced RAID data recovery software is capable of recovering lost or deleted files from various storage devices such as HDDs, SSDs, drives and more.
But DAS is not just limited to HDDs and SSDs. When configured as RAID 5 or RAID 6, this software can help you recover lost data if the hard drive failure is below the fault tolerance of the selected RAID array.
However, a complete RAID failure occurs if the failure of a hard drive exceeds the fault tolerance of the RAID configuration in question. Such a serious scenario leads to a permanent data failure. In such a case, only a backup can help you to restore the data.
Conclusion
Direct Attached Storage is a fast and easy data storage solution that connects directly to a PC. Whether an HDD, SSD, USB device or your internal drive, they are all a form of DAS.
However, these different devices have one thing in common – they are susceptible to data loss. This can happen for any reason, e.g. accidental deletion, formatting, damage, human error, etc. Data loss from DAS media can be a difficult situation for the user. However, with advanced data recovery software, you can recover lost files without much effort.
