SAN vs NAS vs DAS - How it Differs Each Other

This article we will explain the very basic features of SAN and NAS devices. There are a lot storage vendors providing NAS and SAN devices like Dell ( EMC merged), NetAPP, Hitachi, Hewlett Packard Enterprise and IBM. Based on the requirement and features, companies choose different products.

SAN (Storage Area Network)


1) Share storage among different application servers.
2) Data is stored at a block level.
3) Physical elements of the SAN (servers, switches, storage arrays, etc.) are connected with Fibre Channel.
4) SAN is both scalable and flexible
5) Storage can be added without disrupting the applications and the different types of storage can be added to the pool.
5) Backups are centralized due to reducing workload and also providing greater assurance that the backups are complete.
6) Backup traffic never impacts users on the LAN.

NAS (Network Attached Storage) 


1) NAS accesses data by files.
2) NAS manages its own file system.
3) NAS can be accessed across multiple operating systems.
4) NAS backups are more efficient. (With NAS feature called Snapshot provides an almost instantaneous way for the systems administrator to recover lost, deleted or corrupted files.)
5) Administrators can assign shares and security settings as they would for a regular file server.

ISCSI SAN Features

iSCSI presents volumes as a block storage device which makes them ideal for use by enterprise applications such as Microsoft Exchange and Microsoft SQL Server. In particular, the Microsoft iSCSI Software Initiator is the component of the overall iSCSI environment that makes it possible to make the iSCSI SAN attached disks appear to be local attached disks.

1) ISCSI is a lower cost alternative to Fibre Channel SAN infrastructure.
2) Interconnect is ethernet cable and the switches are Gigabit Ethernet.
3) The protocol used is TCP/IP.

DAS (Direct Attached Storage)


1) The disks may be internal to the server or in an array that is connected directly to the server.
2) Backups must either be performed on each individual server.
3) Storage can only be added by taking down the application server, by adding physical disks and then rebuilding the storage array.


Hope this article gave you some basic information about SAN and NAS devices. Please provide your experience and information about storage devices in the comment section.

Bobbin Zachariah 10:50 pm


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