On 02/01/2013 12:17 PM, Dominique wrote:

Hi list,

I was wondering what would be the best way to convert a 6 hdd raid 5 to
raid 6. Ideally without having to reformat everything and lose all the
data in the process. I have backups of the data but I don't look forward
reinstalling everything on that server.

1) Add a seventh drive to the system.

You can do this on the run if you have hotplug-capable sata ports or sas
ports.

2) Add that drive to the array w/ "mdadm --add"
3) Convert array to raid6 w/ "mdadm --grow --level=raid6"

You can do 2 & 3 on the run.

4) Monitor /proc/mdstat to see when it finishes.

HTH,

Phil