Janek Kozicki wrote:

Hello,

I just created a new array /dev/md1 like this:

mdadm --create --verbose /dev/md1 --chunk=64 --level=raid5 \
   --metadata=1.1  --bitmap=internal \
   --raid-devices=3 /dev/hdc2 /dev/sda2 missing


But later I changed my mind, and I wanted to use chunk 128. Do I need
to delete this array somehow first, or can I just create an array
again (overwriting the current one)?

How much later? This will, of course, destroy any data on the array (!) and
you'll need to mkfs again...


To answer the question though: just run mdadm again to create a new array with
new parameters.


I think the only time you need to 'delete' an array before creating a new one is
if you change the superblock version since it quietly writes different
superblocks to different disk locations you may end up with 2 superblocks on the
disk and then you get confusion :)
(I'm not sure if mdadm is clever about this though...)

Also, if you don't mind me asking: why did you choose version 1.1 for the
metadata/superblock version?

David