On Friday 14 January 2005 21:35, Ferenc-Jan wrote:

Hello,

I tried to create a raid5 set with 3 partitions and one missing device:

That should work.

mdadm -C /dev/md1 -R -l5 -n4 /dev/hda3 /dev/hdc3 /dev/hdd3 missing

Maybe it's in the syntax.  What is that -R doing here ?

Later I want to add the fourth device with mdadm /dev/md1 -a /dev/hdb3.

I do 'mdadm -a  /dev/md1 /dev/hdb3'.  Maybe that makes a difference ?

But this becomes a spare and I always end up with the missing drive in
sync, mdadm -D /dev/md1:

<snip>
3       0        0        0      sync

I want to do this so I can use hdb to transfer data from an harddisk to
the raid5 set. Maybe this is only possible with Raid 1 sets?

No, this should be possible.  Many people do this.  

P.S.: You _are_ aware of the dangers of using raid-5 on drives that share the 
same IDE cable ?  I see you use hda+hdb and hdc+hdd...
In practise this could mean that if one drive fails you could lose all your 
data (unless you manually repair / reassemble the array)

(Just making sure you don't make the same mistake I made...)

Maarten