Compex Systems Advanced SerialRAID Adapters SA33-3285-02 - Manual (Page 38)

Configuring Devices on an SSA Loop
If an SSA loop contains three or more SSA adapters that are installed in two or more
using systems, you must ensure that all those using systems are switched on, and that
all the disk drives in all those using systems are configured, as follows:
v If all the using systems are switched off (Micro Channel or PCI):
1. For each Micro Channel system:
a. Set Secure mode on each using system.
b. Switch on all the using systems.
c. Wait for 200 to be displayed on the operator panel of each system.
For each PCI system:
a. Switch on one using system only.
b. Wait for the first display (logo) to appear on the screen. Press F1
immediately. The using system goes into System Management Services
mode.
2. When each using system is in the state described in the preceding steps:
– For Micro Channel systems, set Normal mode to continue the boot process.
– For PCI systems, press F10 (Exit) to continue the boot process.
v If one or more using systems are switched on (Micro Channel or PCI):
1. Switch on the remaining using systems.
2. On each using system:
a. Run the cfgmgr command to configure all the disk drives.
b. Manually vary on the volume groups and mount the file systems as required.
SSA Link Speed
Some SSA devices can run at 20 MB per second; others can run at 40 MB per second.
Both types of devices can exist in a particular configuration, but for best performance all
links should run at the same speed. Two types of SSA cable are available:
v 20 MB per second SSA cables (color coded black)
v 40 MB per second SSA cables (color coded blue).
The speed at which a link runs is automatically agreed between its two nodes. Under
some fault conditions, a link that normally runs at 40 MB per second might run at
20 MB per second. The automatic run_ssa_link_speed diagnostic searches for pairs
of 40-MB-per-second nodes that are running at only 20 MB per second. This diagnostic
is started by an entry in the cron table. If you are using 20-MB-per-second cables to
connect 40-MB-per-second SSA nodes, delete the run_ssa_link_speed entry from the
cron table. This action prevents the logging of errors that can be solved only by the
installation of 40-MB-per-second cables.
18 User’s Guide and Maintenance Information