mirror without destroying existing contents

[David Robillard]

>> Anyone made a mirror w/o destroying what's in the disk already?  The
>> atacontrol man page is less than adequate in this respect...is is even
>> possible?
>
> Oh, yes-- it's certainly possible to create a mirror with live data,
> but one is advised to be cautious and have a full backup available in
> case of problems.  With hardware-based ATA controllers like Promise,
> 3ware, etc, they should have a BIOS utility which you can use to
> create the mirror-- make sure to add the drive with valid data first,
> and then add the second or additional drives to the mirror set.
>
> The same approach ought to work with software-mirroring such as (g)
> vinum.

I'd add gmirror(8) to the list of software RAID solutions.

Man page: http://www.freebsd.org/cgi/man.cgi?query=gmirror&apropos=0&sektion=0&manpath=FreeBSD+6.2-RELEASE&format=html

Handbook:
http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/book.html#GEOM-MIRROR

Cheers,

David
-- 
David Robillard
UNIX systems administrator & Oracle DBA
CISSP, RHCE & Sun Certified Security Administrator
Montreal: +1 514 966 0122