Subject: raidframe: re-mirroring
To: None <>
From: Louis Guillaume <>
List: netbsd-users
Date: 07/24/2004 14:31:02

A while ago I had a raid-1 component fail on me. There was some kind of
DMA error reported on the console and the machine was hung. I suspect
this may have been a driver error, as the drive worked solidly until an
upgrade of the kernel, after which this error came up almost
immediately. The array (of 1) has been working flawlessly since failing
the drive. The other drive continues to be there, spinning as a "failed

It's now a couple kernel builds later and I'd like to try bringing that
disk back into the fold. The question is: how does raidframe know which
drive to consider having the correct data?

For instance - if there is a file on the failed drive that has since
been deleted from the filesystem. Will that file be merged back in to
the system? Or will the data on that disk be completely condemned and
the mirror rebuilt from the only known good disk?

Is there a way to "initialize" a failed component so there is no danger
of merging in unwanted data?

This brings up another point. Say I wanted to upgrade the system. I'd
guess its a good idea to "break the mirror", i.e. fail one component and
upgrade to the other.

If the upgrade works then bring the failed component back in (provided
it's data will be condemned).

If it doesn't, revert to having the failed component as the prime disk.
How can this be done if it's failed?

The confusion is: How does raidframe know which disk has the data you
want to keep in a raid-1 situation? How can you tell it to rebuild from
one drive and not the other?

Any help would be great,