RAID level 5 question

[James Ralston]

On 2004-03-31 at 08:24:34-0600 "Rodolfo J. Paiz" <rpaiz at simpaticus.com> wrote:

> At 05:14 3/31/2004, you wrote:
> 
> > I'm thinking about setting up a software raid level 5.
> > Is it possible to start with 3 HDs and then later add more?
> > I mean, without loosing the data on the first 3 HDs.
> 
> Yes, on most *good* hardware RAID cards and also (I think) on Linux
> software RAID.

Linux software RAID (md) cannot do this: you can add and remove
hotspares at will, but the number of active disks in the RAID 5 array
is set when the array is created, and cannot be changed.

If you're using RAID 1+0 (i.e., striping across a series of mirrors),
you can do what you want by juggling degraded arrays.

-- 
James Ralston, Information Technology
Software Engineering Institute
Carnegie Mellon University, Pittsburgh, PA, USA