Rebuilding a Raid 1

Kristian Rasmussen kristian.rasmussen at
Sat May 18 13:51:48 UTC 2013

On 18.05.2013 15:26, Danny wrote:
> Sorry Kristian, by fakeraid I meant softraid.
> I actually boot off an mdadm RAID0 on my main system. SO it is not a
> requirement to use bios raid to boot off of these raid types.

With the exception of RAID 0, the advantage of BIOS support is the
ability to boot from a degraded array.

It is certainly possible to boot from a RAID array without BIOS support
as long as the boot loader supports it. I have a number of systems
booting from RAID 1 sets using LILO and an initrd with mdadm, but should
the primary disk fail, the BIOS will probably still try to boot from the
broken drive and fail.

The only sensible way to set up fakeRAID is to use a driver with proper
metadata support. Right now that driver doesn't exist for the vast
majority of RAID5 fakeRAID systems unless one uses an older kernel and
dmraid. For RAID1 arrays, dmraid still works with recent kernels.

mdadm only supports Intel arrays and according to the developers, this
situation is unlikely to change.

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