36.2. Rescue Mode on POWER Systems

You can use the installation disks in rescue mode, in case your system does not boot. Rescue mode gives you access to the disk partitions on your system so you can make any changes necessary to rescue your installation.

After the Language Selection screen (Section 15.2, “Language Selection”), the installation program attempts to mount the disk partitions on your system. It then presents you with a shell prompt where you can make the changes you need. These changes may include storing the kernel and command line into the IPL source, as described in the Installation Complete section (Section 16.20, “Installation Complete”).

When your changes are complete, you can exit the shell using exit 0. This causes a reboot from the C side. To reboot from the A or B side or from *NWSSTG, you should vary off the system instead of exiting the shell.

36.2.1. Special Considerations for Accessing the SCSI Utilities from Rescue Mode

If your system uses Native DASD disks, you may need access to the SCSI utilities from rescue mode. These utilities are located on the driver disc CD. The driver disc CD cannot be mounted from rescue mode unless special steps are taken. These steps are described below.

If you have a second CD-ROM drive assigned to your Linux system, you can mount the driver disc CD in the second drive.

If you have only one CD-ROM drive, you must set up an NFS boot, using the following steps:

Boot from the CD-ROM with the linux rescue askmethod command. This allows you to manually select NFS as the source of your rescue media instead of defaulting to the CD-ROM drive.
Copy the first installation disc onto a file system of another Linux system.
Make this copy of the installation disc available through NFS or FTP.
Vary off or power down the system you need to rescue. Set its IPL parameters as instructed for booting the Installation discs in rescue mode, except that the IPL source should point to the copy of boot.img on your IFS (from step 1, above).
Make sure the installation disc is not in your DVD drive.
IPL the Linux system.
Follow the prompts as decribed in Section 36.2, “Rescue Mode on POWER Systems”. An additonal prompt for the installation source appears. Select NFS or FTP (as appropriate) and complete the following network configuration screen.
When the Linux system has booted into rescue mode, the CD-ROM drive is available for use and you can mount the driver media to access the SCSI utilities.