Re: RAID superblock confusion

Neil Brown (neilb@cse.unsw.edu.au)
Thu, 11 Apr 2002 13:18:33 +1000 (EST)


On Wednesday April 10, mfedyk@matchmail.com wrote:
> On Thu, Apr 11, 2002 at 11:38:19AM +1000, Neil Brown wrote:
> > autodetect is the other alternative. However, as has been mentioned,
> > it does not and cannot work with md as a module. This is because
> > devices can only be register for autodetection after md.o is loaded,
> > and autodetection is done at the time that md is loaded. So
> > autodetection can only work if the device driver and md are loaded at
> > simultaneously. i.e. they are compiled into the kernel.
>
> Ahh, but if you use initrd you can even have the ide and scsi drivers as
> modules.
>
> What is needed is to make the disk modules depend on the raid modules (only
> if the raid code is enabled of course) so that modprobe can load the raid
> modules first.
>
> Then you'd just need to make sure that if there are any block modules linked
> into the kernel that raid is also linked into the kernle instead of
> a module.

Woah... I think you are going off the deep end here. This sounds just
too complicated.

1/ If you wanted to do autodetect "right", you would make it look a
lot like partition detection (split md into two bits. A partition
detection personality that registers the component devices
somewhere, and the main raid module that gets autoloaded when you
try to actually access a raid device).
2/ Partition detection *should* be done in user-space. So should
autodetect. mdadm does that for you..

NeilBrown
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