Common storage systems

Data is a critical asset or component of any enterprise and they access it regularly for various purposes. Enterprises deploy various storage systems for this purpose. Common storage systems include SAN, NAS and DAS  and therefore, they are the subject of this article.

What is SAN?

SAN stands for Storage area network and it is one of the common storage networking architecture. It is used by enterprises when they run business critical applications which require high throughput and low latency. 

It is a block based storage and connects servers with logical units or LUNs. A LUN is actually a range of blocks from shared storage pool.

SAN storage devices include tape libraries, and disk based devices like RAID etc. Following are some of the components of SAN technology.

1. Switch
2. Storage devices
3. Servers
4. SAN management software
5. Cables

Protocols

Following are some of the SAN protocols.

1. FCP
2. iSCSI
3. FCoE
4. FC-NVMe

Advantages

Following are some of the advantages of SAN.

1. Scalability
2. Performance
3. Data isolation
4. Workload isolation
5. Uptime
6. Long distance connectivity
7. Increased utilization
8. Centralized management

Disadvantages

Following are some of the disadvantages of SAN.

1. SANs are very expensive as they use fiber channel technology
2. Management of SAN systems are really tough
3. Due to high prices, there are few SAN product vendors

What is NAS?

NAS is a storage device which is connected with a local area network and it is used to provide a centralized storage for various users and clients. These are less expensive, faster and flexible devices and you can easily add them to your existing infrastructure when you are required an additional storage.

Protocols

There are several protocols which are used to access the data in a Network Attached Storage. I have listed some of the following here:

1. NFS (Network File System)
2. CIFs (Common Internet File System)
3. NCP (Network Communication Protocol)
4. AppleTalk
5. FTP (File Transfer Protocol)
6. HTTP (Hypertext Transfer Protocol)

Advantages

Following are some of the advantages:

1. NAS devices are simple to operate and they do not require dedicated IT professionals
2. They have lower  cost
3. Data can be backed up easily and when required can be accessed in few minutes

Disadvantages

Following are some of the disadvantages:

1. Performance of NAS depends on the available bandwidth
2. NAS appliances consumes bandwidth

What is DAS?

DAS or Directly attached storage is a type of storage that is directly attached with a computer system. It is connected with a single computer and none of other computers can access it. For individual computers, hard disks and solid state drives are part of DAS. However, in enterprise network, a collection of hard disks are directly connected with servers and they are accessed by using some protocols. It is often referred to as bunch of disks (JBoD).

Protocols

Following are some of the protocols which are used in DAS technology.

1. SCSI
2. SATA
3. SAS
4. FC
5. iSCSI

Advantages

Following are some of the advantages of DAS.

1. Gives better performance because storage is directly attached and no network is involved for reading and writing the data
2. It is less expensive than NAS and SAN
3. It is easier to deploy

Disadvantages

Following are some the disadvantages of DAS.

1. It lacks many advanced storage management features as compared with NAS and SAN

Vendors

Following are some the vendors in NAS, SAN and DAS market.

1. Dell EMC
2. HPE
3. NetApp
4. IBM
5. Huawei
6. Oracle
7. Lenovo
8. Fujitsu
9. Western Digital
10. Hitachi Data Systems

Virtual Storage Area Network (VSAN)

StarWind has introduced a virtual storage area network or VSAN. It eliminates the need of physical shared storage by mirroring internal hard disks and flash between hypervisor servers. It doesn’t need any proprietary components.

VSAN offers following benefits.

1. Exceptional simplicity
2. Cost efficiency
3. Performance and features