Planning and Preparation

When adding an interface card online, the first issue that must be resolved is whether the new card is compatible with the system. Each OL* capable PCI slot provides a set amount of power. The card to be added cannot require more power than is available. Some systems may have only one slot per bus with sufficient power.

The card must also operate at the slot’s bus frequency. “Frequency Mismatch”.

When a card is added to the system, the appropriate driver for that card must be configured in the kernel before beginning the operation. In most cases, the added card should be the same type as a card already in the system, and the driver will be in the kernel. Kernel Configuration is accessible through kcweb. If the required driver is not present, a reboot will be required to load the driver. The card could be added while the system is down, or added online after rebooting. A reboot may not be needed if the OS version supports Dynamic Loadable Kernel Modules (DLKM).

When replacing an interface card online, the replacement card must be identical. This is referred to as like-for-like replacement and should be adhered to because using a similar card, but not identical, may cause unpredictable results. For example, a newer version of the target card which is identical in terms of hardware may contain an updated firmware version that could potentially conflict with the current driver. If a new card is not acceptable, pdweb will report that the card cannot be resumed, the Attention Button method will result in the slot not being powered up, and olrad will return an error.

The PCI specification allows a single physical card to contain more than one port. Attempting to replace a card with another card that has more ports than the original could result in the additional port(s) being claimed by other drivers if an ioscan occurs while the slot power is on. The ports would be claimed properly, and recovering from that condition would require a system reboot.