Naming is the mapping between logical and physical objects. In a conventional file system, it's understood where the file actually resides; the system and disk are known. In a transparent DFS, the location of a file, somewhere in the network, is hidden. File replication means multiple copies of a file; mapping returns a SET of locations for the replicas.
- Location transparency -
* The name of a file does not reveal any hint of the file's physical storage location.
* File name still denotes a specific, although hidden, set of physical disk blocks.
* This is a convenient way to share data.
* It can expose correspondence between component units and machines.
- Location independence :
* The name of a file doesn't need to be changed when the file's physical storage location changes.Dynamic, one-to-many mapping.
* Better file abstraction.
* Promotes sharing the storage space itself.
* Separates the naming hierarchy from the storage devices hierarchy.
A location independent naming scheme is a dynamic mapping, since it can map the same file name to different locations at two different times. Therefore, location independence is a stronger property than location transparency.
Most DFSs today support location transparent systems. They do not support migration and files are permanently associated with specific disk blocks.
Wednesday, February 3, 2010
Naming and Transparency in Distributed File Systems
Posted by Sunflower at 2/03/2010 02:44:00 PM
Labels: DFS, Distributed file systems, File systems, files, Location Independent, Location transparent, Naming, Naming structures, Operating Systems, Transparency
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