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In this thesis, we will describe the design of a distributed
file manager to provide the ability to access files on any
other nodes and to support parallel file I/O on
Cohesion : a distributed shared memory (DSM) system developed
in our lab.Most of the current DSM systems use release
consistency protocol to maintain memory coherency,which can
obtain better performance.As far as file access is
concerned, however there exists I/O problems.One efficient
scheme to improve performance is utlizing parallel file I/O. It
is necessary that any station can access files on any
station for such a parallel file system. Before achiving this
aim, We implement a distributed file manager with shared file
offset . The file manager provides efficient file services
for applications. Moreover, this manager can access the
files on the other nodes and it is also provided with cache
function supporting parallel file I/O. In distributed shared
memory system,momery consistency manager resloves the memory
coherency between all nodes.While design cache machanism, we
can keep cache on distributed shared memory and rely
consistency manager to maintain cache coherency. It is easier
to build. In this thesis,we adopt two different approaches to
design the distributed file manager. One is to build user-
level cache library, which coherence is maintained by the
memory consistency manager in the kernel level.Another approch
uses message-passing and token to maintain cache consistency
in kernel. Both of them use write-on-close policy to write
files back to disk.The first scheme is simpler to achieve,but
the performance is dependent on the whole DSM environment. The
performance of the second scheme effected by the algorithm and
consistency policy.We will compare the performance and discuss
the result.
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