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