Configuring HP-UX For Peripherals

Chapter 2 39

Managing PCI Cards with OLAR

PCI Card OLAR Overview and Concepts

automatically, and presents options to you based on it’s ﬁndings. If

critical resources will be affected by the procedure, you can replace the

card off-line, or you can use either rad or SAM to perform an on-line

addition of a backup card that can then be conﬁgured as a backup, and

then replace the target card.

Note that SAM will only analyze cards as follows:

• Mass storage cards will be analyzed for:

— Mounted ﬁle systems

— Usage by a process

— Dump or swap usage

• Network interface cards (NICs) will be analyzed for:

— Usage by the active SAM session

Fail-over Actions / Single Points of Failure

In most cases, the system will automatically fail over to the alternate

resource when a card is suspended. However, some subsystems might

require manual intervention. For example, the Logical Volume Manager

(LVM), will automatically redirect I/O for a temporarily disconnected

disk resource to a mirror, logging errors as it handles this situation.

• Along those lines, if the resource will be suspended for an extended

period of time, a large number of error log entries could result.

• In this type of situation, you may want to manually switch over to a

mirror beforehand. When you have completed the OLAR procedure,

the mirror and disk can be re synchronized.

If you suspend a card and the backup takes over, the system can contain

a single point of failure. If the backup resource fails before the new card

is on-line, the system could potentially crash. This window of

vulnerability can be minimized by keeping the period of suspension as

short as possible. This requires careful planning, and gathering as much

information as possible before actually suspending driver operation and

powering-down a card slot.

When an extended suspension period is unavoidable, or when the system

is mission-critical, it is desirable to conﬁgure a second backup resource if

possible.