Kbase 16476: Improving performance of probkup and prorest using -bf
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
10/05/1998 |
|
Improving performance of probkup and prorest using -bf
Performance on probkup will be at it's best when we can keep
the tape drive streamed. A tape drive being streamed means
it never has to wait for data to put on the tape. When a
tape drive is not streamed, you can hear the tape start and
stop moving.
Knowing that we write to the tape drive everytime will fill
up a -bf block, one could say "why not use a -bf of 1" so
we don't do any buffering. The problem with this approach
is the process writing to the tape drive will block until
the tape drive can respond to the write request. This is
why we buffer up some blocks. In addition, if you set the
-bf parameter below the tape block size, the I/O to the
tape may be ineficient.
The converse is setting the -bf too high will cause the tape
drive to wait for data to be written because we are spending
too much time filling up the buffer. It takes time to get
the tape to start and stop, so you don't want to do this
either.
The best approach is to experiment with the -bf parameter
with your tape drive to find the best performance. You should
benchmark probkup as well as prorest.
Progress Software Technical Support Note # 16476