As discussed at the beginning of this chapter, one of SCO ARCserve/Open's key features is its ability to run jobs concurrently.

You can have up to 7 tape drives connected to your host using your host's primary SCSI port. You can also divide these tape drives into ``groups''. By default, SCO ARCserve/Open is installed with one group for each tape drive that is attached to your host. These default groups are named after the planets in our solar system, excluding Earth. (The planets are Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto.) Therefore, if you have two drives, SCO ARCserve/Open will set up two groups called ``MERCURY'' and ``VENUS''. You can then modify these tape group assignments using the instructions over the next few pages.

If you have multiple groups, you can attach drives to each group and take advantage of ``parallel streaming''. Parallel streaming means that you can have more than one job running at a time. For example, you could assign drives 1 and 2 to a group called ``GROUP1'' and assign drives 4, 5, and 6 to a group called ``GROUP2''. You could then have a backup job running at GROUP1 while a restore job runs at GROUP2.

If you group drives into a single group, you will be able to take advantage of ``drive spanning'', where when one tape becomes full, the backup session automatically spans to the next drive in the same group.

Since jobs being run are set within their own distinctive groups, ``parallel streaming'' and ``Drive Spanning'' can occur concurrently.

There is really only one rule for grouping tape drives: each tape drive in a group must be identical (same brand and model).

When you install SCO ARCserve/Open, the drives are automatically grouped for you. If you have five drives attached to the server, regardless of whether they are all identical, you will have five groups.

After you start SCO ARCserve/Open, you can:

• add a tape group

• remove a tape drive from a tape group

• add a tape drive to a tape group

• delete tape groups