On Fri, Nov 24, 2017 at 06:54:43PM -0800, Paul Chambers wrote:

(all the detailed info is at the end of this email)

I could use some expert help...

I started with a RAID-5 array of 5 x 6TB WD RED drives, and 1 x 6TB
Seagate Ironwolf drive. This has been running well for a long time as
a 5-drive array, and was grown to a 6 drive array a few months ago by
the addition of the ironwolf drive. No known issues.

  ### devices in order: 0   1   2   3   4   5
  DRIVES="sdj sdg sdf sdq sdc sdh"

I purchased 3 x 8TB WD Red drives, and used parted to set them up as
GPT, with a single partition that fills the drive.

I then added them to the array in the usual fashion:

~# mdadm --add /dev/md0 /dev/sdi /dev/sdk /dev/sdl

Hmm.. what was the point of creating the partitions if you added the whole disk to the array anyway? 


-- Pasi