CSE 124 Lecture Notes - Lecture 9: European Cooperation In Science And Technology, Cache Coherence, File Locking
23 Apr 2018
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Document Summary
Want higher-level abstractions like directories, files, links, etc. Make a remote file system look local . Mount remote fs (host:path) as local directories. Nfs client - intercepts system calls and handles these (read,write,open,close, etc. ) Remote os will use the correct fs and sends response back through the nfs server, through the socket, and back to the client. Vfs / local fs fd = open ( path , flags) read (fd, buf, n) - reads n bytes of data write (fd, buf, n) Implicit pointer to the offset of the file where we finished reading. Essentially duplicating it (2*n bytes contain 2 copies of the file!) close (fd) Server maintains state that maps fd to inode , offset. Stateless nfs: strawman 1 fd = open( path , flags) read( path , buf, n) write( path , offset, buf, n) close(fd) Strawman 2 read( path , offset , buf, n) write( path, offset , buf, n)
