Branch for my Google SOC RAID and LVM work

[Jeroen Dekkers]

Hi all,

I just created a CVS branch ("google-soc2006") withthe work I've done
so far for my Google SoC project. I currently have support for reading
RAID0, RAID1 and RAID5 arrays (the most common ones) finished. The
init function of the module currently scans all devices for a RAID
superblock. This won't work when modules containing devices are added
after the RAID module is loaded, but as far as I know GRUB should
already know about all devices when the RAID module is loaded, so this
shouldn't be a problem. The code also supports reading from degraded
RAID arrays, it is be able to read things when the RAID1 array has
only one disk and when the RAID5 array is missing one disk.

The current code has some loose ends, those all marked with
FIXMEs. First of all GRUB should probably also support less common
RAID levels like RAID4, RAID6, RAID10 en linear mode. Secondly the
RAID0 code currently assumes that all members of the array have the
same size, but this doesn't have to be the case.

Another issue is that since Linux 2.6 supports a new superblock layout
which I've not implemented yet. Currently mdadm still creates old
superblocks by default, so this shouldn't cause big problems at the
moment. Linux 2.6 also added support for partitions on RAID arrays,
this isn't implemented either. The last important issue is that RAID5
support different layouts for the parity, I've only implemented the
default layout so far.

Because this a Google SoC project, it has to be 100% my own work. So
don't send me patches, I can't really do anything with them at this
moment. If you try out the code and find problems, please report them
and I'll fix them myself.

The next thing I'm going to work on is adding support for RAID devices
in grub-setup. It should automatically detect whether /boot is on a
RAID device and set everything up accordingly when this is the case.


Jeroen Dekkers