Re: Newbie questions: Max Active disks, RAID migration, Compiling mdadm 2.3

On Sunday February 5, ritchiem@mac.com wrote:

I can see what I did now. Very silly.

I created a RAID 5 with 4 disks then went about hot adding disks.  
Silly me thinking it would increase the active space. Of course with  
the parity being shared through the active disks this doesn't makes  
sense.

I was wanting to define a systematic way that I could start with a  
small number of disks and then expand the RAID as I needed more space  
(and could afford more disks).

Is raidreconf the only way for reconfiguring a live system?

raidreconf doesn't allow you to reconfigure a live system - only an
inactive system.
But for the moment, that is the only way, yes.

In 2.6.17 or 2.6.18 it should be possible to restripe a raid5 to have
a larger number of devices.  This can happen while the array is in
active use.
The code is mostly written, and could be used today, but I don't
recommend it on valuable data yet as there are known bugs.

NeilBrown