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Over this cheat sheet you can find information about some characteristics related to NAS/SAN storage systems.
NAS: Network Attached StorageA 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 |
| | SAN: Storage Area NetworkStorage 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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