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Informative NAS/SAN Cheat Sheet (DRAFT) by

Over this cheat sheet you can find information about some characteristics related to NAS/SAN storage systems.

This is a draft cheat sheet. It is a work in progress and is not finished yet.

NAS: Network Attached Storage

A NAS device (“appl­ian­ce”), usually an integrated processor plus disk storage, is attached to a TCP/IP­-based network (LAN or WAN), and accessed using specia­lized file access­/file sharing protocols. File requests received by a NAS are translated by the internal processor to device requests.

Charac­ter­istics

* A NAS device is attached to a TCP/IP based network (LAN or WAN)
* Accessed using CIFS and NFS — specia­lized I/O protocols for file access and file sharing
* A NAS device is sometimes also called a file server, or “filer” or “NAS appliance”
* Receives an NFS or CIFS request over a network and has an internal processor which translates that request to the SCSI block-I/O commands to access the approp­riate device
* Works through ethernet media
* Has a 10Mbps to 1Gbps bandwith
* Works with NFS and CIFS I/O Protocol
* In contrast to “block I/O” used by DAS and SANs, NAS I/O requests are called “file I/Os”
* A NAS appliance generally supports disk storage, and sometimes CD-ROM, in an integrated package
* NAS device is generally only a NAS device and attaches only to processors over a LAN or WAN

Advantages

* Easier to install
* NAS appliance can usually be installed on an existing LAN/WAN network
* Hosts can potent­ially start to access NAS storage quickly, without needing disk volume defini­tions or special device drivers
* NAS pooling can minimize the need to manually reassign capacity among users
* Provides file sharing
* NAS devices often can handle several thousand I/Os per second with good average response time
* Large number of users being able to access the same storage device

Disadv­antages

* More expensive than DAS
* As the number of NAS nodes increases, cost do as well
* Less faster than SAN
* NAS will generally not scale as well as SAN in perfor­mance
* Buying an integrated NAS means less time

Applic­ation Enviroment

* Data sharing, staging, and movement between various host systems
* Data access by Unix, Linux, NT, and others
* Data sharing including Internet Web content for Web server farms
 

SAN: Storage Area Network

Storage resides on a dedicated network. Like DAS, I/O requests access devices directly. Today, most SANs use Fibre Channel media, providing an any-to-any connection for processors and storage on that network.

Charac­ter­istics

* Dedicated network for storage devices and the processors that access those devices
* SANs today are usually built using Fibre Channel technology
* I/O requests to disk storage on a SAN are called “block I/Os"
* Longer distance between processors and storage
* Higher availa­bility
* Improved perfor­mance
* A larger number of processors can be connected to the same storage device compared to typical built-in device attachment facilities
* Software can allow multiple SAN devices to appear as a single pool of storage accessible to all processors on the SAN
* Storage on a SAN can be managed from a single point of control

Advantages

* All devices on a SAN can be pooled­—mu­ltiple disk and tape systems
* Easier to manage
* Provides file sharing
* Faster than NAS
* Use of a dedicated network (though this is possible with NAS).
* SAN network speed (100MBps Fibre Channel vs. 10Mbitps or 100Mbitps Ethernet)
* More scalable

Disadv­antages

* Less easier to install than NAS
* Take more time planning, including design of a Fibre Channel network and select­ion­/in­sta­llation of SAN management software
* More expensive than NAS
* Require specia­lized hardware and software to manage the SAN and provide many of its potential benefits
* An organi­zation must add new skills to manage this sophis­ticated technology

Applic­ation Enviro­nment

* Storage or server consol­idation
* Perfor­mance sensitive with low latency including database and OLTP
* Large I/Os or data transfer applic­ations
* LAN-free or Serverless backup

Advantages

* Easier to install
* Can be installed on an existing LAN/WAN network