Rebooting from an alternative source
When you reboot Linux®, the system conventionally boots from the last used location. However, you can configure an alternative device to be used for re-IPL instead of the last used IPL device.
- Linux must be compiled to support rebooting from an alternative source. This feature is built into the kernel by default.
- The IBM Z® hardware must have zfcp IPL support for re-IPL from SCSI devices.
Use the chreipl tool to configure the re-IPL device.
Alternatively, you can use a sysfs interface. In sysfs, the virtual configuration files are located under /sys/firmware/reipl. To configure, write strings into the configuration files. The following re-IPL types can be set with the /sys/firmware/reipl/reipl_type attribute:
- ccw
- For ccw devices such as DASDs that are attached through ESCON® or FICON®, and for virtio block devices on KVM guests.
- fcp
- For FCP SCSI devices, including SCSI disks and CD or DVD drives (Hardware support is required.)
- nss
- For Named Saved Systems (z/VM® only)
For each supported re-IPL type a sysfs directory is created under /sys/firmware/reipl that contains the configuration attributes for the device. The directory name is the same as the name of the re-IPL type.
When Linux is booted, the re-IPL attributes are set by default to the values of the boot device, which can be found under /sys/firmware/ipl.