load balancing question

John E. Malmberg wb8tyw at qsl.net
Wed Oct 9 11:34:00 GMT 2002

To clear up some confustion in this thread.

A DFS will only help distribute the load if the clients are accessing 
files in different directories.

\\host\share\dir1\   would be served by host_1
\\host\share\dir2\   would be served by host_2
\\host\share\dir3\   would be served by host_3

If all the clients are reading the same file say in \host\share\dir1\ 
then using the DFS does not help at all.  All the requests will be 
handled by host_1.

If you have a fail-over disk system that is common to the three hosts, 
then dir1, dir2, dir3 can be moved from one host to another as needed, 
but the move is time consuming, and still one host at a time.

In a shared access disk system such as in an OpenVMS cluster, you have 
the following:

\\host\share\dir1\   would be served by host_1, host_2, and host_3, ...
\\host\share\dir2\   would be served by host_1, host_2, and host_3, ...
\\host\share\dir3\   would be served by host_1, host_2, and host_3, ...

With an I.P. alias, clients can be connected to any host and still have 
access.  This will load share.

And DFS has no involvement in the scheme, and provides no advantage.

DFS only helps if the clients are reading files out of different 
directories, which is not how I am interpreting the information in the 
post that started this thread.

DFS can be enhanced to allow a better fail over mechanism for the 
platforms that do not support simultaneous access to a common disk.  But 
that is not load balancing.  All clients accessing the same directory 
are either all on the same host, or one host will have direct access, 
and the rest will be taking a second indirect path through the network.

Locking is an issue.  Samba 2.0.6 for OpenVMS uses file system locking, 
and the slower share locking.  I am not sure about the 2.2.4 port.

wb8tyw at qsl.network
Personal Opinion Only

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