Cache Consistency
Let's look at the cache consistency problem with respect to the AFS.
We'll cover the following...
When we discussed NFS, there were two aspects of cache consistency we considered: update visibility and cache staleness. With updated visibility, the question is: when will the server be updated with a new version of a file? With cache staleness, the question is: once the server has a new version, how long before clients see the new version instead of an older cached copy?
ASIDE: CACHE CONSISTENCY IS NOT A PANACEA
When discussing distributed file systems, much is made of the cache consistency the file systems provide. However, this baseline consistency does not solve all problems with regard to file access from multiple clients. For example, if you are building a code repository, with multiple clients performing check-ins and check-outs of code, you can’t simply rely on the underlying file system to do all of the work for you. Rather, you have to use explicit file-level locking in order to ...