howto software raid under FreeBSD?

Emanuel Strobl Emanuel.Strobl at
Sun Oct 31 10:30:08 PST 2004

Am Sonntag, 31. Oktober 2004 19:01 schrieb Matthias F. Brandstetter:
> ---------- quoting Emanuel Strobl ----------
> > Why going outside and searching the internet?
> > You have a complete operating system, and it's one of the best
> > documented out there. Just 'man ata', 'man atacontrol' and 'man
> > gmirror'. Remember that FreeBSD isn't just a hacked kernel with lots of
> > stuff arround without any sense, it's standardized an documented! ;)
> Ok, I looked at "man gmirror", but found nothing for my 5.2.1 system. As
> you mentioned, gmirror is for 5.3 only.
> I missed "man atacontrol", sorry for this. Now I've looked at its man page,
> looks good. Only one problem: man page says that I can only rebuild an
> RAID1 array on RAID capable ATA controllers. But I have no such "real" ATA
> controller. How can I replace a faulty disk with atacontrol on a normal
> ATA controller then?

You can use 'atacontrol detach' then powerdown, replace the drive and after 
booting you can 'atacontrol addspar ar0 ad6' (or what ever drive and array 
failed) and 'atacontrol rebuild ar0'.
I've done some "simulation" of this but never had a real failed drive, also I 
never checked data integry by md5 sums or something like that.
One important thing:
If you "simulate" the failure by 'atacontrol detach' make sure to wipe out the 
first and last sectors of the "failed" disk, because otherwise ata would 
detect two raid arrays when booting next time and if you "failed" the first 
drive you get messed up!


> Thanks for your help, Emanuel!
> Greetings, Matthias
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