Distributed Files System Flashcards
What is the primary purpose of a distributed file system?
To enable programs to store and access remote files as if they were local
What are the key requirements for sharing within local networks and intranets?
Persistent storage of data and programs, consistent distribution of up-to-date data
What features were added to file systems for data and program sharing?
Access-control mechanisms and File-locking mechanisms
What advantages does a well-designed file service provide?
Access to files with performance and reliability similar to, or better than, local disks
How does the concentration of persistent storage at servers benefit organizations?
Reduces local disk storage needs and enables better management and archiving of persistent data
What additional services can be implemented more easily with a file service?
- Name service
- User authentication service
- Print service
What are the responsibilities of file systems?
- Organization of files
- Storage and retrieval of files
- Naming and sharing of files
- Protection of files
What is the role of directories in file systems?
To provide a mapping from text names to internal file identifiers
What does the term ‘metadata’ refer to in the context of file systems?
Extra information needed for the management of files, including file attributes and directories
What elements are typically included in a file’s attribute record?
- Length of the file
- Timestamps
- File type
- Owner’s identity
- Access control lists
File systems are designed to manage a small number of files
False
What is the purpose of a directory in a file system?
To support the naming of files and allow for hierarchic file-naming schemes
What types of operations are summarized for applications in UNIX systems?
System calls implemented by the kernel for file operations
The data in a file consists of a sequence of _______
Data items
What were the initial offerings of distributed file systems?
Access transparency and location transparency.
What requirements emerged in the development of distributed file systems?
Performance, scalability, concurrency control, fault tolerance, and security.
What were the potential pitfalls observed in distributed services design?
Many of the requirements and potential pitfalls were first observed in the early development of distributed file systems.
What is the importance of the file service in an intranet?
The file service is usually the most heavily loaded service in an intranet, so its functionality and performance are critical.
What are the transparency requirements for distributed systems?
- Access transparency
- Location transparency
- Mobility transparency
- Performance transparency
- Scaling transparency
What is meant by concurrent file updates?
Changes to a file by one client should not interfere with the operation of other clients simultaneously accessing or changing the same file.
What standards do current file services follow for locking?
Modern UNIX standards in providing advisory or mandatory file- or record-level locking.
In a file service that supports replication, a file may be represented by several copies of its contents at different locations.
File replication in a service
Why is fault tolerance important in a file service?
The central role of the file service in distributed systems makes it essential that the service continue to operate in the face of client and server failures.
Refers to a model for concurrent access to files where all processes see the same file contents as if only a single copy existed.
Consistency
What challenges arise with file replication and caching?
There is an inevitable delay in the propagation of modifications made at one site to other sites, which may result in deviation from one-copy semantics.
What security measures do file systems provide?
Virtually all file systems provide access-control mechanisms based on access control lists and require authentication of client requests.
What is the goal of efficiency in a distributed file service?
A distributed file service should offer facilities at least as powerful as conventional file systems and achieve comparable performance.
