Topic: how to add an 3rd hard drive

[pbearne]

Hi Guys

I have found a extra hard drive the same size as by mirror software raid

So can I add this without having to rebuild the server?

if so how?

Paul

[bpivk]

Yes and you really should figure out how to use the search button by now (seeing that you have 50 posts).

And you know... we have a wiki.

http://wiki.contribs.org/SME_Server:Documentation:Technical_Manual:Chapter5

[pbearne]

Hi guys

sorry I didn't ask the question quite right

I all ready have 2 drives that are mirrored I now want to add an third hard drive go from raid1 to raid5

I can't find instuction to do this?

Paul

[Gaston94]

Hi
as far as I know you cannot convert a raid1 structure to a raid5 one.
something that can be done , on your own responsability and with all required pre backup job done and check :
 - split your RAID1 array
 - reinitialize one of your disk superblock (mdadm --zero-superblock /dev/sdxx)
 - create a degraded RAID 5 array with the new disk and the one you get from your splitted RAID1 one (saying one disk is missing)
 - copy your datas from your RAID1 to your RAID5
 - definitely stop your RAID1 array
 - reinitialize superblock of this disk
 - join last disk to the new RAID5 array

well these are only ideas I am putting there. This is not a HOWTO, and I have never tryied it.
Always think that when something can go wrong it will, so cross check you have correct backup.

G.
PS I found on the net someone with a close approach but creating a degraded RAID5 array on two disks. I didn't knew this can be done ...

[CharlieBrady]

I all ready have 2 drives that are mirrored I now want to add an third hard drive go from raid1 to raid5

RAID5 on only three disks is not recommended.

[munter]

I all ready have 2 drives that are mirrored I now want to add an third hard drive go from raid1 to raid5

RAID5 on only three disks is not recommended.

down on 3 disks in raid 5 is allmost like having a singeldisk in safety