IBM 4690 - Manual (Page 19)

Master on primary IDE:
C: drive
Slave on primary IDE:
none
Master on secondary IDE:
D: drive
Slave on secondary IDE:
tape drive
In the configuration above, you do not need to change the jumper on the tape
drive, but you may need to change the jumper on the D: drive. Some hard
disks have three possible jumper settings:
v master
v master with a slave attached
v slave
If you have one of these hard disks and it is currently a “master with no slave”
and you are adding the tape drive as a “slave”, then you must change the
jumpers on the hard disk from “master” to “master with a slave attached”. The
C: drive does not contend with other devices. The D: drive does contend with
the tape drive. If a tape operation is in progress, a file access to the D: drive
must wait for the tape drive to complete a command before starting the file
access. Any application waiting for the file access to complete cannot run
during this time.
Alternatively, if a file access to the D: drive is in progress, the tape drive must
wait for the file access to complete before a tape operation can begin. This may
cause an underrun and the tape drive must stop, rewind a little, and start
forward again, which impacts tape drive performance. The configuration above
may be best when you have two hard disks and you have no need to run the
tape drive while other applications are actively accessing the D: drive. There is
no contention between the C: and D: drive.
Configuration 4
Master on primary IDE:
none
Slave on primary IDE:
none
Master on secondary IDE:
tape drive
Slave on secondary IDE:
none
The configuration above assumes that all of your hard disks are SCSI instead of
IDE. In this configuration, you must configure the tape drive as the master
(MA) by placing a jumper over vertical pins 5 and 6. There is no contention for
the devices.
2. Refer to your store controller documentation to determine if your store
controller supports the cable select (CS) feature. With the cable select feature
there is a special cable and the placement of the devices on the cable connectors
determines whether a device is master or slave if the devices are set to CS.
Most store controllers do not use this cable feature.
Chapter 2. Tape Drive Installation 5