Root RAID HOWTO cookbook: Appendix G. - linuxrc theory of operation

14. Appendix G. - linuxrc theory of operation

This is the complex form of the linuxrc file for root mounted raid. It must be processed with 'bash' or another shell that recognizes shell functions.

The advantage is that it is generic and is not dependent on startup files and parameters located in the initrd image.

A Raid_Conf parameter passed to linuxrc by the kernel at boot from lilo or loadlin contains a pointer to the boot devices and location the of initial 2 raidboot files needed by linuxrc (raidboot.etc and raidboot.cfg placed by the shutdown script).

raidboot.etc containing the 'tar'ed files:
        raid*
        mdtab*
        fstab
        lilo.conf               ( if applicable )
from the primary system that are transferred to the initrd /etcetc directory at startup. With care, this file may be edited if necessary when your system 'really' crashes.
raidboot.cfg contains the name of the boot partition in use and applicable backup(s) as well as the path to the rest of the raid start up file used by linuxrc. This file is normally created by the shutdown file and may be created manually if necessary.
raidboot.cfg is of the form, 3 lines - no comments
        /dev/bootdev1 /dev/bootdev2 [/dev/bootdev3 ... and so on]
        raid-status/path 
        name_of_raidX.conf_file
the raid-status/path does not include the name of the mountpoint
the raidX.conf filename is that one found in /etc and normally used for ckraid and mkraid.

The following additional files reside on the permanent raid boot partitions. This is usually the same as above, but in emergency situations may be loaded from anywhere they are available, such as a floppy boot disk.

raidgood.ref created by the command cat /proc/mdstat | grep md0 > /{raid_status_path}/raidgood.ref
See the shutdown scripts for saving this file and the next
raidstat.ro created at each shutdown by the shutdown rc file, saving the exit status of the raid array.

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