The hard disk drives with "NAS" in their name are functionally similar to other drives but may have different firmware, vibration tolerance, or power dissipation to make them more suitable for use in RAID arrays, which are sometimes used in NAS implementations. For example, some NAS versions of drives support a command extension to allow extended error recovery to be disabled. In a non-RAID application, it may be important for a disk drive to go to great lengths to successfully read a problematic storage block, even if it takes several seconds. In an appropriately configured RAID array, a single bad block on a single drive can be recovered completely via the redundancy encoded across the RAID set. If a drive spends several seconds executing extensive retries it might cause the RAID controller to flag the drive as "down" whereas if it simply replied promptly that the block of data had a checksum error, the RAID controller would use the redundant data on the other drives to correct the error and continue without any problem. Such a "NAS" SATA hard disk drive can be used as an internal PC hard drive, without any problems or adjustments needed, as it simply supports additional options and may possibly be built to a higher quality standard (particularly if accompanied by a higher quoted MTBF figure and higher price) than a regular consumer drive.
Principal of Operation
NAS systems contain one or more hard disk drives, often arranged into logical, redundant storage containers or RAID.
NAS uses file-based protocols such as NFS (popular on UNIX systems), SMB/CIFS (Server Message Block/Common Internet File System) (used with MS Windows systems), AFP (used with Apple Macintosh computers), or NCP (used with OES and Novell NetWare). NAS units rarely limit clients to a single protocol.
Why is NAS gaining popularity?
Network administrators are always on the lookout for dependable, expandable, and easy-to-install options to alleviate server storage overload. NAS fills the bill. Basically, NAS removes the file-server function from overloaded general-purpose servers. It does this via a specialized, high- performance network-attached file server, sometimes referred to as a "filer."
On a network, data-access time determines how rapidly you can do your job. For instance, how fast securities traders process orders, how quickly product designers can get their wares to market, and how promptly corporate intranet users can download a file depends, in part, on data-access time. NAS devices ensure users fast and reliable access to data.
What are some of the factors to consider before implementing NAS?
The first thing you look at is how many users you have on the system. Are there enough users to justify [buying a NAS device]? Next, you look at what the users are doing when they log onto the server, because if you have 50 clients and all 50 need to log onto the same Unix machine, they have to go through seven million lines of code essentially to get to their data. What that does is place an undue overhead on that machine. It`s supposed to be number-crunching, but it can`t because you have clients trying to access their data. That`s when you consider using a NAS device to offload those clients.
How NAS provides Data backup and Disaster Management
NAS units typically has software to either copy your specific directory or the entire drive in an incremental fashion. Typically system administrator creates a schedule that all the workstations my document directory will be backed up during 12-6 AM in the network. By automating the backup procedure completely, the data loss and IT disaster can be mitigated completely. For a more complex scenario the NAS can be configured in a more comprehensive fashion.
NAS is useful for more than just general centralized storage provided to client computers in environments with large amounts of data. NAS can enable simpler and lower cost systems such as load-balancing and fault-tolerant email and web server systems by providing storage services. The potential emerging market for NAS is the consumer market where there is a large amount of multi-media data. Such consumer market appliances are now commonly available. Unlike their rackmounted counterparts, they are generally packaged in smaller form factors. The price of NAS appliances has plummeted in recent years, offering flexible network-based storage to the home consumer market for little more than the cost of a regular USB or FireWire external hard disk. Many of these home consumer devices are built around ARM, PowerPC or MIPS processors running an embedded Linux operating system.
We provide NAS & SAN solutions and complete SMB disaster management . Please contact our Applications Engineer for details.
1,0 NETGEAR NAS
2.0 Buffalo NAS
3.0 WD NAS
4.0 ADATA NAS
5.0 IT Disaster Recovery Featured Article
6.0 Keendirect NAS Offering KEENDIRECT NAS