The Cache Consistency Problem

In this lesson, we learn what the crash consistency problem is and how NFS addresses it.

The cache consistency problem is best illustrated with two clients and a single server. Imagine client C1 reads a file F, and keeps a copy of the file in its local cache. Now imagine a different client, C2, overwrites the file F, thus changing its contents; let’s call the new version of the file F (version 2), or F[v2] and the old version F[v1] so we can keep the two distinct (but of course the file has the same name, just different contents). Finally, there is a third client, C3, which has not yet accessed the file F.

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