Mumbai University > Computer Science > Sem 8 > Parallel And Distributed System
The specific client's request for accessing a particular file is serviced on the basis of the file accessing model used by the distributed file system.
The file accessing model basically depends on 1 ) the unit of data access and 2 ) the method used for accessing remote files.
On the basis of the unit of data access, following file access models might be used in order to access the specific file.
- File-level transfer model
- Block-level transfer model
- Byte-level transfer model
- Record-level transfer model
1.File-level transfer model: In file-level transfer model, the complete file is moved while a particular operation necessitates the file data to be transmitted all the way through the distributed computing network amongst client and server. This model has better scalability and is efficient.
2.Block-level transfer model: In block-level transfer model, file data transfers through the network amongst client and a server is accomplished in units of file blocks. In short, the unit of data transfer in block-level transfer model is file blocks. The block-level transfer model might be used in distributed computing environment comprising several diskless workstations.
3.Byte-level transfer model: In byte-level transfer model, file data transfers the network amongst client and a server is accomplished in units of bytes. In short, the unit of data transfer in byte-level transfer model is bytes. The byte-level transfer model offers more flexibility in comparison to the other file transfer models since, it allows retrieval and storage of an arbitrary sequential subrange of a file. The major disadvantage of byte-level transfer model is the trouble in cache management because of the variable-length data for different access requests.
4.Record-level transfer model: The record-level file transfer model might be used in the file models where the file contents are structured in the form of records. In record-level transfer model, file data transfers through the network amongst client and a server is accomplished in units of records. The unit of data transfer in record-level transfer model is record.