Interface Card OL* Support Guide

Chapter 1
PCI Card OL* Overview and Concepts
Important Considerations
21
WARNING If a card with a shared slot is added or replaced, a frequency or bus-mode mismatch
could cause the OL* operation to fail.
The following example would fail.
Step 1. Suspend a PCI-X card
Step 2. Resume or add a PCI card
Frequency Mismatch
The card must also operate at the slot’s bus frequency. A PCI card can run at a frequency lower than its
maximum capability. A card added that has a higher frequency than the slot will run at the slower slot speed.
Cards with a slower frequency may not be able to be installed in a slot with a higher frequency. The pdweb tool
provides information about the bus frequency and power available as well as other slot-related data.
The following table shows the consequences of installing a card into a slot with different frequencies.
Table 1-2 Frequency Matching Scenarios for Shared Slots
Slot 1 Slot 2 Comments
Add empty No frequency issue. The slot/card operates at an optimum frequency.
empty Add No issue. The slot/card operate at an optimum frequency
Add Add The first card to be added in decides the slot's operating frequency. If the
second card could match this frequency, the second Add succeeds, otherwise
the Add operation fails.
Add Replace The first card to be up (Added or Replaced) decides the slot's operating
frequency. If the second card (Added or Replaced) could match the slot's
operating frequency, the operation succeeds, otherwise the second operation
fails.
Table 1-3 Installing Card into a Slot with a Different Frequency
Relative Card / Slot
Frequency
Consequences Exceptions
Lower Higher Bus drops to match
lower frequency
If this is a shared frequency domain, the installation
would be rejected to prevent slowing down an already
running card.
Higher Lower Card speed drops to
match bus speed