Setup of a software RAID-1 to an existing system?

Thomas McIntyre temac at
Sun Jun 22 15:36:40 PDT 2003


The canonical answer is to repost to freebsd-questions, which enjoys
a larger readership.  But I'll try -- your question is interesting
b/c I'm in the same boat, except w/ CURRENT.  As you said, breezing
through the handbook will show a lot of detail, but perhaps it does
not directly address mirroring a live fs.

Aside from the handwaving, you might check 
There seems to be a relevant (if a little dated) article:

It may be possible to mirror partitions, even if half of it is live. 
Were this not the case, it's prob possible to boot the install cdrom
and play some tricks with dd or dump to sync the disks.  Perhaps they
could then be mounted, vinum set up, and then booted into.  

It would be fantastic if the freebsd installer had the ability to run
raid 1 right out the chute.  Doubtless, there's a number of us w/
legacy servers having two disks but no hardware raid.

Good luck.  Share your notes (at least to newbies) once you get it

Tom McIntyre

-----Original Message-----
From: Johan Paul [mailto:mailing-lists at]
Sent: Sunday, June 22, 2003 12:19 PM
To: freebsd-newbies at
Subject: Setup of a software RAID-1 to an existing system?

Hi all!

I am pretty new to FreeBSD but thought it might be a nice idea to 
migrate from a Linux server to a FreeBSD one.

My question is regarding software RAID-1 for this FreeBSD box. I have

two IDE equally sized hard drives and I installed FreeBSD 4.8 on the 
other one. Now the question is: can I make a RAID-1 array of these
disks while FreeBSD is installed on the other one (using vinum or 
other...)? Or how do I get RAID-1 to work on these two disks?

I've read some of the vinum documentation but it is unclear to me if
is possible to set up a RAID-1 on a running disk system - and if my 
assumptions are correct, that it is impossible, it is unclear to me
to set up this RAID-1?


Johan Paul

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