[AFS3-std] Re: [OpenAFS-devel] convergence of RxOSD, Extended Call Backs, Byte Range Locking, etc.

[Jeffrey Altman]

Matt W. Benjamin wrote:
> Ok, sure.  But I believe what you are describing is not invalidation, but rather replacement.  It's not incorrect to use "invalidate" referring to "data."  This precisely means (some specialization of, such as a message indicating) the data as known is not valid, not that replacement data is delivered.  As you state, XCB has operations that replace metadata, but (as with the traditional AFS callback) only invalidate data.  
XCB has the ability to replace or update metadata.  It also has the
ability to "validate" cached data.  A callback that indicates that
between DV=N and DV=N+1 the following set of data ranges were altered
also asserts that if the cache contains data in other ranges tagged with
DV=N, it is now DV=N+1.  data within the invalidated ranges must be
purged.  That is the important gain that XCB messages sent as a result
of StoreData and MiniData operations provide.

Jeffrey Altman