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. 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. 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. For example, some NAS versions of drives support a command extension to allow extended error recovery to be disabled. Īccompanying a NAS are purpose-built hard disk drives, which are functionally similar to non-NAS drives but may have different firmware, vibration tolerance, or power dissipation to make them more suitable for use in RAID arrays, a technology often used in NAS implementations. From the mid-1990s, NAS devices began gaining popularity as a convenient method of sharing files among multiple computers, as well as to remove the responsibility of file serving from other servers on the network by doing so, a NAS can provide faster data access, easier administration, and simpler configuration as opposed to using general-purpose server to serve files. Network-attached storage typically provide access to files using network file sharing protocols such as NFS, SMB, or AFP. NAS systems are networked appliances that contain one or more storage drives, often arranged into logical, redundant storage containers or RAID. It is often manufactured as a computer appliance – a purpose-built specialized computer. The term "NAS" can refer to both the technology and systems involved, or a specialized device built for such functionality (as unlike tangentially related technologies such as local area networks, a NAS device is often a singular unit).Ī NAS device is optimised for serving files either by its hardware, software, or configuration. Network-attached storage ( NAS) is a file-level (as opposed to block-level storage) computer data storage server connected to a computer network providing data access to a heterogeneous group of clients.
0 kommentar(er)
