Performing an alternate IPL

The process of performing an IPL from removable media is an alternate, or type D, IPL. The device that contains the IPL media is the alternate IPL device. The alternate IPL device is attached to the system either internally or externally.

In almost all cases the HMC is used to select the device that will be used for the alternate IPL (see Alternate restart device in the Partitioning for i5/OS® topic). If the alternate IPL device has not been configured by using the HMC or by a previous alternate IPL, see Default search sequence for the alternate IPL device below.

Default search sequence for the alternate IPL device

The system attempts an IPL from the first alternate IPL device it finds that is ready and contains IPL media.

Note:

On non-HMC managed models 515, 520, 525, 550, or 570, the system will only Alt IPL from the internal DVD ROM or tape drive. If you are using an external device, the Alt Install device must first be selected. This is because the manufacturer sets the Alt IPL to the internal SCSI controller on the system backplane and it cannot be changed.
Once the system has successfully performed an alternate IPL, the Virtual Service Processor (VSP) will remember the address of the device and use it for any subsequent alternate IPLs until either the HMC is used to select a different alternate IPL device or the alternate IPL fails. Once an alternate IPL fails the VSP will go back to using the default search sequence.

The following IOA slot will be used:

For model 515, 520, 525: bus 3, slot 005
For models 550 and OpenPower® 720: bus 3, slot 004
For model 570: bus 3, slot 007

The following search sequence is used to search for an alternate IPL device attached to the IOA:

Device attached to SCSI bus 0 with a controller address of 7 (SCSI address 0).
Device attached to SCSI bus 0 with a controller address of 6 (SCSI address 1).
Device attached to SCSI bus 0 with a controller address of 5 (SCSI address 2).

If the system cannot find a device to use as the alternate IPL device, it displays a reference code on the control panel.

Note: The reference code that is displayed is for the most severe error that is found during the search sequence for the alternate IPL device. There may not be an association between the error and the alternate IPL device that you are using. Before using the displayed reference code to analyze the problem, ensure that the alternate IPL device is ready and contains the correct IPL media.

External device addressing

The external alternate IPL device must have a controller address of 7, 6, or 5. For most devices, the controller comes with the address preset to 7, and you cannot alter it. For devices that have changeable addresses, use the following information:

For 34xx, 35xx, and type 7208 model 342 tape devices you must set the SCSI address to 0, 1, or 2. For an IBM® 9427 8mm tape cartridge library, you must set the tape library address for the drive that is used as the alternate IPL device to 0, 1, or 2.

For the location of the address switch on external devices, see the information in the device service manual.