DragonFly kernel List (threaded) for 2006-05
Re: The Clustering and Userland VFS transport protocol - summary
Matthew Dillon wrote:
In a clustered environment the execution context (what 'cp' is actually
running on) can be anywhere. But there is absolutely no reason for the
file data to physically pass through that machine if 'cp' itself does
not need to know what the file contains. If done properly, the actual
file data would be transported directly from machine A to machine B,
or stay strictly within machine A in the second example.
Are such operations going to be exposed through system calls? In other
words, does this mean that userland utilities will need to be modified
to fully support (efficiently) this type of copy by reference?
What level of transactional support will be provided? For example, will
the cp utility return before or after the data itself is made durable?
Will it be possible for the cp utility to complete successfully, have
the node containing the referenced cache data fail and thus the
transaction fail after the fact?
What are the error recovery/failure scenarios in the case that a node
with the only copy of referenced cached data fails?
Best of luck with your work, and thank you!