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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
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* A NAS device is attached to a TCP/IP based network (LAN or WAN)
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* Accessed using CIFS and NFS — specialized I/O protocols for file access and file sharing
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* A NAS device is sometimes also called a file server, or “filer” or “NAS appliance”
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* 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
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* Works through ethernet media
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* Has a 10Mbps to 1Gbps bandwith
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* Works with NFS and CIFS I/O Protocol
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* In contrast to “block I/O” used by DAS and SANs, NAS I/O requests are called “file I/Os”
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* A NAS appliance generally supports disk storage, and sometimes CD-ROM, in an integrated package
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* NAS device is generally only a NAS device and attaches only to processors over a LAN or WAN
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* Easier to install
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* NAS appliance can usually be installed on an existing LAN/WAN network
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* Hosts can potentially start to access NAS storage quickly, without needing disk volume definitions or special device drivers
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* NAS pooling can minimize the need to manually reassign capacity among users
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* Provides file sharing
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* NAS devices often can handle several thousand I/Os per second with good average response time
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* Large number of users being able to access the same storage device
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* More expensive than DAS
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* As the number of NAS nodes increases, cost do as well
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* Less faster than SAN
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* NAS will generally not scale as well as SAN in performance
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* Buying an integrated NAS means less time
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* Data sharing, staging, and movement between various host systems
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* Data access by Unix, Linux, NT, and others
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* Data sharing including Internet Web content for Web server farms
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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
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* Dedicated network for storage devices and the processors that access those devices
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* SANs today are usually built using Fibre Channel technology
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* I/O requests to disk storage on a SAN are called “block I/Os"
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* Longer distance between processors and storage
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* Higher availability
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* Improved performance
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* A larger number of processors can be connected to the same storage device compared to typical built in device attachment facilities
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* Software can allow multiple SAN devices to appear as a single pool of storage accessible to all processors on the SAN
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* Storage on a SAN can be managed from a single point of control
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* All devices on a SAN can be pooled—multiple disk and tape systems
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* Easier to manage
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* Provides file sharing
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* Faster than NAS
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* Use of a dedicated network (though this is possible with NAS)
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* SAN network speed (100MBps Fibre Channel vs. 10Mbitps or 100Mbitps Ethernet)
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* More scalable
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* Less easier to install than NAS
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* Take more time planning, including design of a Fibre Channel network and selection/installation of SAN management software
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* More expensive than NAS
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* Require specialized hardware and software to manage the SAN and provide many of its potential benefits
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* An organization must add new skills to manage this sophisticated technology
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* Storage or server consolidation
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* Performance sensitive with low latency including database and OLTP
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* Large I/Os or data transfer applications
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* LAN-free or Serverless backup
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