>From: Dearman, Richard [mailto:rdearm1 AT UIC DOT EDU]
>>Why would I send the data to tape first writing to disk is faster.

"Burton, Robert" wrote:
> Tape direct is a heck of a lot faster than disk....

Let's qualify that a bit.

Since the major bottleneck in tape operations are file openings and file
closures, staging the backup of a lot of small files to disk first, and
then to tape later, is much faster than directly to tape.

Large files are a different matter. The larger the file, the closer that
tape speed approaches disk speed. As tape speed increases, it makes
little sense to write to disk *and* then write to tape. The other reason
to stage to disk first is if you're concurrently backing up multiple
clients.

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.

As has been said before, you need to go to gigabit ethernet, connected
with a switch, and use TSM's multithreading to get maximum throughput.

--
Mark Stapleton (stapleton AT berbee DOT com)
Mark Stapleton (stapleton AT berbee DOT com)

--
Mark Stapleton (stapleton AT berbee DOT com)
Mark Stapleton (stapleton AT berbee DOT com)