Cannot boot from initrd into RAID1

Cannot boot from initrd into RAID1

[paul kölle]

Hi list,

well, I won't bother you with the whole story, so just the important
facts. I have to use initrd because I need to preload the module for the
 SATA Controller (4port Marvell). I have 4 disks with /<root> and a few
other partitions on RAID1 and others on RAID5. I made a raidtab config
and build the arrays with no problems, created fstab an can mount all
partitions from my boot/rescue system just fine. The problem is booting
the system. After loading the SATA module, linuxrc tries to mount
/dev/md0 (which is supposed to be /<root>) and fails with input/output
error. ^D -> rescue shell let me do cat /proc/mdstat wich shows
something like:
<identities>  [raid1 raid5]

but no arrays. I wonder if I need a statically built binary of mdadm or
thelike in initrd to initialize the arrays or should a proper configured
kernel just do fine?

thanks
 Paul

Re: Cannot boot from initrd into RAID1[solved]

[paul kölle]

paul kölle wrote:
> Hi list,
> 
> well, I won't bother you with the whole story, so just the important
> facts. I have to use initrd because I need to preload the module for the
>  SATA Controller (4port Marvell). I have 4 disks with /<root> and a few
> other partitions on RAID1 and others on RAID5. I made a raidtab config
> and build the arrays with no problems, created fstab an can mount all
> partitions from my boot/rescue system just fine. The problem is booting
> the system. After loading the SATA module, linuxrc tries to mount
> /dev/md0 (which is supposed to be /<root>) and fails with input/output
> error. ^D -> rescue shell let me do cat /proc/mdstat wich shows
> something like:
> <identities>  [raid1 raid5]
> 
> but no arrays. I wonder if I need a statically built binary of mdadm or
> thelike in initrd to initialize the arrays or should a proper configured
> kernel just do fine?
replying to myself:

As it turned out the problem is that if RAID support is compiled into
the kernel but the driver for the disk controller is a module the kernel
tries to init the RAID but the disks aren't there yet because the module
is loaded later from the initrd system.

There are two possible solutions:

1. Build all RAID support as modules and make sure the modules are
loaded in the correct order from initrd. Than with partitions set to FD,
the kernel should be able to access the /dev/md* devices (haven't tried
this actually).

2. Include a statically build version of mdadm or raidstart into the
initrd and run it (through linuxrc) *after* the disk controller has been
initialized and *after* the device nodes have been populated by udev.


cheers
 Paul

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