Storage Types (DAS, NAS & SAN) - Networkwalks Academy

What is storage? Why we need storage?

Storage is the collection of methods and technologies that can capture and hold digital information on media. Storage is normally described as the data storage devices that are connected to the computer through input or output operations that includes flash devices, hard disks, SAN, NAS, old tape systems and other different types of medium.

Storage Types

There are a lot of options that are available for storing data. The main purpose is deciding which is the most appropriate for you. All are different on the basis of their need and usage criteria e.g. CD, Punch card, Zip disk, DVD, Blu-ray disc, Flash jump drive, Hard Drive, Floppy diskette, NAS, Tape drive, SSD (Solid State Drive), NAS and Cloud Storage. For example, we are using USB Flash drives for our students data management here at Network Walks Academy.

1. DAS (Directly Attached Storage)

This is as simple as it sounds DAS (Directly Attached Storage) device. A simple example of DAS is an external hard drive connected through a Universal Serial Bus (USB) cable. When we discuss about storage, we mean multiple drives, array of disks acting together in some way. The DAS concept is the same whether it’s one or 24 drives. In the same way it is the same concept regardless if we use a different cable. Basically, USB is much slow for large DAS units. DAS is well suited for a small-to-medium sized business where enough amounts of storage can be configured at a low startup cost. The DAS enclosure can be a separate cabinet that contains the additional disk drives. An internal PCI-based RAID controller is typically configured in the server to connect to the storage.

Advantages of DAS

It is simpler to setup and configure over NAS / SAN
It is very cost effective than NAS / SAN in terms of raw storage medium
It does not use IP addresses. Network is not necessary, Faster, more preformat and better latency over SAN / NAS
Easier to deal with overall considering all things

Disadvantages of DAS

Dedicated resources are needed for a single computer
No economies of scale in sharing the storage
We cannot manage the DAS via a network
DAS needs a special hardware connection

2. NAS (Network Attached Storage)

Every computer that is irrespective of number of disks and the size of storage space available, can be considered a NAS if it acts as a file server on the network. Another way, a network attached storage (NAS) device is just a computer that shares files over the network. Theoretically it is almost identical to the external USB hard drive, except instead of a USB cable connection, a NAS will be using an Ethernet connection or some networking cable like LAN. NAS devices have a shareable resource. Multiple users and computers can use that resource. The disk arrays in both NAS and DAS are similar in function and operation, meaning you can create similar RAIDS and partition styles on both. NAS is perfect for SMBs and organizations that need a minimal-maintenance, reliable and flexible storage system that can quickly scale up as needed to accommodate new users or growing data.

Advantages of NAS

It is the economical way to provide large storage to many persons or computers
It is several times easier to setup and configure versus SAN
It is easier way to provide RAID redundancy to mass amount of users
It allows users permissions, folder privileges, restricted access to documents, etc
It has higher utilization of storage resources

Disadvantages of NAS

It requires IP Address and takes up network space
It has slower latency and potentially maximum data-transfer issues
It performance can be affected by network status

3. SAN (Storage Area Network)

SAN stands for Storage Area Network. With SAN we typically see the solutions that are used with medium-to-large size businesses, primarily due to the larger initial investment. SANs require a setup consisting of disk controllers, SAN switches, host bus adapters and fiber cables. The main benefit to a SAN-based storage solution is the ability to share the storage arrays to multiple servers. This allows you to configure the storage capacity as needed, usually by a dedicated SAN administrator. Higher levels of performance throughput are typical in a SAN environment and data is highly available through redundant disk controllers and drives. SAN is typically used in data centers, enterprises or virtual computing environments. It offers the speed of DAS with the sharing, flexibility and reliability of NAS. SAN storage is a very sophisticated option that’s meant to support complex, mission-critical applications.

Advantages of SAN

It has economies of scale similar to that of NAS
It has higher hardware utilization, similar to that of NAS
It has speed similar or comparable to DAS
It allows virtual environments, cloud computing, etc.

Disadvantages of SAN

Its performance is affected by other SAN users
Its performance is limited by network if configured incorrectly
Better performance will still be found using DAS hardware
It requires multiple static IP Addresses
It generally consumes more IP addresses than NAS devices

So, which storage type is best for my network?

The choice of the network type that you will use is all depends upon the best storage option for your business. Once you know which factors are essential to your business operations, you can find the storage option to fit your particular need there.

	DAS	NAS	SAN
Protocols	SATA, SAS	SMB (CIFS), NFS	iSCSI, Fiber Channe
Type	File Storage	Block Storage	Block Storage
Speed	5-10ms	5-10ms	20-50ms
Data Transmission	IDE/SCSI	Ethernet, TCP/IP	FiberChannel
Complexity	Easy	Moderate	Complex
Management Costs	High	Moderate	Low
Storage Type	Sectors	Shared Files	Blocks
Supports Capacity Sharing?	No (possible manually)	Yes	Yes
Connected to Network or not?	No	Yes	Yes
Scalability	Low	Medium	High

Summary

To summarize the whole topic, there are many types of storage solutions that can be used in a Data Center & Windows environment. The main categories/types are DAS, SAN and NAS. This article will expand your knowledge by focusing on the nuts and bolts of implementing storage solutions. The main differences between the types are startup costs, whether the storage is shared or dedicated, and whether additional storage can be added on-demand. Different technologies are also used to connect and control the storage such as SAS, Fiber and many more mediums.

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