Re: RAID-1 to RAID-5 online migration?

[Ralph Paßgang <ralph@debianbase.de>]

Am Donnerstag 02 September 2004 15:18 schrieb Mark Janssen:
> On Thu, 2004-09-02 at 13:43, Gavin Hamill wrote:
> > Hello -  just a quickie :)
> >
> > If I construct a RAID1 with two 200GB disks, will I be able to add a
> > third disk and convert the whole set to a 400GB RAID5 later on by
> > logically removing the second disk from the RAID1 set?
>
> Nope... migrating to a different raid configuration wipes your disks
> So you'll have to backup, migrate and restore.

Yes, but you can make something like this:

remove one drive from the raid-1. You get an dregraded, but normal working 
raid1 array.

create a new raid5 for three disks, but you add only two disks to the raid5. 
So you are building a dirty raid array, but this should works. (never tested 
it myself with a raid5, only with a raid1)

Now you can copy the data from your degraded raid1 to your new raid5.

After that is done you can delete the old raid1 completly and add the now free 
disk to the raid5...

But be carefull, if you make something wrong you can loose all data, so making 
a backup is of course the better and the secure way.

--Ralph