On 2 May 2001, at 22:53, Mark Stapleton wrote:
>Where does the trade off happen for your system? There
>are so many
>variables that it is almost mandatory to do some
>benchmarking to find
>the breakpoint.

Questions like this are extremely complex. Every single piece in the
system must be looked at to determine bottlenecks and best solutions.
A partial list would include:

        - size of files being backed up
        - number of files being backed up
        - rate that files can be read from disk
        - read datastreams from the same disk
        - rate that client can send data
        - network topology between client/server
        - rate that server can receive data
        - concurrent data streams into the server
        - tape drive speed (streaming, start/stop)
        - buss speed to tape drive
        - concurrent data streams for multiple tape drives
                sharing a single buss
        - compressability of data
        - I/O capability of tsm server
        - cpu speed of tsm server

Any one of these can be a bottleneck that destroys
backup performance.  And no, there is not an easy way
to figure all this out.  Probably the hardest thing I find
for myself is to not make assumptions.  Every single piece
of the puzzle must be looked at!

Rick