Saturday, 15 November 2014

                       SAN and NAS

NAS and SAN both are enterprise level storages solution for storing data.

NAS: Network attached storage

  • Any server/device that shares its own storage with others on the network and acts as a file server is the simplest form NAS.
  • NAS uses an Ethernet connection for sharing files over the network. The NAS device will have an IP address, and then will be accessible over the network through that IP address. When you access files on a file-server of your organisation from your windows /Linux/ mac system, it’s basically NAS.
  • A client sends a file read/write request to NAS device/server. This request can be CIFS (from Windows OS) or NFS (from Linux OS) or simply HTTP (form web browser), or FTP.  NAS server serves this request.
  • NAS is file level storage (file sharing technology); it hides actual file system underhood.
  • NAS is cheaper technology and it can be setup without any modification on existing system as it works on TCP/IP model.
  • NAS suffers High latency because Ethernet also carries local traffic due to which NAS cannot be used for high performance applications.

SAN: Storage area network 

  • SAN is a high-speed network of storage devices that also connects those storage devices with servers. It provides block-level storage that can be accessed by the applications running on any networked servers. SAN storage devices can include tape libraries, and more commonly, disk-based devices, like RAID.
  •  It is a dedicated storage network that provides block level access to lun (virtual disk provided by SAN).
  •  When a LUN is mapped to a host (let’s say windows initiator), host can see this LUN as new local drive.  
  • A SAN is used to transport data between servers and storage resources. SAN technology enables high-speed connectivity from server to storage, storage to storage, or server to server.
  • The purpose of a SAN server is to store large amounts of data over a network enabling multiple users to share the same storage space simultaneously SAN uses FC and/or iSCSI protocol as communication protocol between SAN device and host (server).
  • SAN can also use ATA over Ethernet (AoE), Fibre Channel over Ethernet (FCoE), ESCON over Fibre Channel as communication protocol.

  1. SAN environment is costly to implement.
  2. SAN provides high speed storage sharing system.
  3. SAN increases the network bandwidth and reliability of data I/O.
  4. SAN is separated from the regular network system and has an ability to expand the storage capacity.
  5. 5.   SAN provide safety by implementing concept of zoning.

Hybrid SAN + NAS

Many organizations prefer such environment where a file server may need have very large storage space that may be not available as local hard disk.
This requirement can be fulfill by SAN storage in very well manner. So a NAS device can use features provided by SAN.


DAS (direct attached storage ) : It is a storage system directly attached to a server or workstation, without a storage network in between them. (more)


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