Unformatted text preview: (Cont.)
Goal: transparent sharing of file systems
• A remote directory is mounted over a local file system
directory. The mounted directory looks like an integral
subtree of the local file system, replacing the subtree
descending from the local directory.
• Specification of the remote directory for the mount
operation is nontransparent; the host name of the remote
directory has to be provided. Files in the remote directory
can then be accessed in a transparent manner.
• Subject to access-rights accreditation, potentially any file
system (or directory within a file system), can be mounted
remotely on top of any local directory. NFS
NFS Mount Protocol
Establishes initial logical connection between server and
Mount operation includes name of remote directory to be
mounted and name of server machine storing it.
• Mount request is forwarded to mount server running on server
• Export list – specifies local file systems that server exports for
mounting, along with names of machines that are permitted to
/usr/home: client1.cs.umn.edu, client2.cs.umn.edu, ….
/bin: client10.cs.umn.edu, client11.cs.umn.edu, … Mounting
Mounting and Path-name Translation
Path3 independent file systems U mount /usr/local to be S1: /usr/shared
S1 mount /usr/shared to be S2: /dir2/dir3 NFS
Following a mount request that conforms to its export list,
the server returns a file handle—a key for further
File handle – a file-system identifier, and an inode number
to identify the mounted directory within the exported file
The mount operation chan...
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- Summer '14
- Operating Systems, file systems, Distributed file system, NFS Architecture