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Unformatted text preview: ges only the user’s view and does
not affect the server side.
/usr/local to S1: /usr/shared, client gets (fsId, remote inode)
/usr/local assoc. with (fsId, remote inode) + server Mount
Static: at boot-time
Automounting: on demand, when a mount point would be
crossed, do the mount
supports multiple options:
/usr/home: s1:/usr/d1/home, s2:/usr/d2/home, … NFS
Provides a set of remote procedure calls for remote file operations.
The procedures support the following operations:
• searching for a file within a directory
• reading a set of directory entries
• manipulating links and directories
• accessing file attributes
• reading and writing files NFS
NFS servers are stateless; each request has to provide a
full set of arguments.
- file locking handled by a separate protocol Three
Three Major Layers of NFS Architecture
UNIX file-system interface (based on the open, read, write,
and close calls, and file descriptors). Access transparency
Virtual File System (VFS) layer – distinguishes local files
from remote ones /usr/fac05 vs. /tmp
• The VFS activates file-system-specific operations to handle
• Calls the NFS protocol procedures for remote requests NFS
NFS service layer – bottom layer of the architecture;
implements the NFS protocol. Schematic
Schematic View of NFS Architecture NFS
Very lose approximation to Unix semantics
read sees last write
Caching is used heavily on client side
reads: 8K, read-ahead, time-limited liveness of blocks, 3 sec
writes (fill 8K, then send, or every 30 sec)
Updates are not immediately propagated … Break
NFSv3 has poor scaling
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This document was uploaded on 04/02/2014.
- Summer '14
- Operating Systems