Vital System Resources

You cannot dynamically detach a PCI card that controls vital system resources unless alternate paths to those resources are available. The alternate paths must be available through a different PCI card or an on-board controller integrated into the system motherboard or system I/O board. Before detaching the card, you must switch control of the vital resources over to the alternate path (note that some multipathing software may handle this automatically). Examples of vital system resources include the system's boot disk, swap space, and primary network interface.

Some cards cannot be detached. A PCI card is not detachable if it controls a boot drive for which no alternate path is available.

If possible, the system's swap space should reside on two or more disks attached to controllers on separate boards. For example, some of the swap space might be controlled by a PCI host adapter card, while the rest could be controlled by the system's on-board controller. With this kind of configuration, a particular swap partition is not a vital system resource, because swap space is accessible through multiple controllers, and additional swap space can be dynamically configured via the swap(1M) command.

Before detaching a PCI card that controls disk swap space, you must ensure that the system's remaining memory and disk swap space will be large enough to accommodate currently running programs.