Subject: Re: "Root on... dumps on..."
To: Malcolm Herbert <>
From: Kevin Brunelle <>
List: netbsd-users
Date: 11/05/2006 01:05:08
On Sunday 05 November 2006 00:17, Malcolm Herbert wrote:
> How does this behave in cases where we are using RAIDFrame? I'm using it
> for my root disk and booting from it directly ... if the kernel needs to
> create such a dump, how will this interact with RAIDFrame when it tries
> to dump to /dev/raid0b as advertised?

You should not do that.

Here's a good article explaining what to do but I will try and cover 
the relevant parts.  Note, I don't currently have this setup myself but I am 
looking into it for someone.

/dev/raid0a     /               ffs     rw      1       1
/dev/raid0b     none            swap    sw      0       0
/dev/raid0e     /home           ffs     rw      1       1
/dev/wd0b       none            swap    dp      0       0

In this case, /dev/wd0b is aligned with the part of /dev/raid0b that is on 
wd0... you'll have to read the article to get a full understanding.  
Basically, this way the kernel knows the actual disk areas where to dump the 
information.  You need to use swapoff to avoid parity errors and such.

In practice I am not sure how well all this works or what effect it has on 
swapping.  But if you're concerned about this and you are unlikely to ever 
use a dump... just turn off dumps entirely.

Add the following line to /etc/sysctl.conf


I hope you're less confused than I am after writing that.  Basically, don't 
dump to raid0b... either use the solution from that link or turn dumping off.