Service Mode
A disk drive must be placed in Service Mode before it can be removed from the SSA
loop and maintenance performed on it. When Service Mode is set:
The Check light of the disk drive comes on for identification.
All SSA loop activity through the disk drive stops.
The disk drive motor stops.
The Check light (if present) of the enclosure that contains the selected disk drive
comes on.
The SSA loop is broken and no communication to the disk is possible.
Only one disk drive at a time can be in Service Mode.
Before using this service aid, you must make the selected disk drive unavailable to the
system; otherwise, an error occurs.
SSA devices can be maintained concurrently; that is, they can be removed, installed,
and tested on an SSA loop while the other devices on the loop continue to work
normally. If a disk drive has its Check light on, you can remove that disk drive from the
SSA loop without taking any special actions.
If a disk drive does

not

have its Check light on, the SSA loop that passes through it
might still be active, although the disk drive itself might not be working. You must put
that disk drive into Service Mode before you remove it from the SSA loop.
To Set Service Mode with the DOS Configurator
1. Start the DOS Configurator (see “Accessing Service Aids from the DOS
Configurator” on page 29) and select SSA Adapter List.
2. Select the required adapter from the list, then from the Adapter Menu select Disk
Service Aids.
The Disk Service Aids window is displayed.
Service Aids and Other Utilities 31