It's been a while since I configured a raid and have been making some changes to my main workstation/server.

fdisk does not like md devices on my machine... always says it has an invalid partition table. While this is said to be normal all over the net, I don't feel warm and fuzzy about that fact.

What is best practice these days, to create a non-partitionable md device or a partitionable mdp device?

If I create a partitionable md device, I would imagine it would look good in fdisk. However, I am concerned about growing the array afterward. I would then have to grow the array, redefine the partition, and then grow the file system.
The PITA factor goes up. Has anyone worked with both? Pro/Cons?

My array was created with:

mdadm --create --verbose /dev/md0 --level=5 --force --raid-devices=3 /dev/sda1 /dev/sdb1 /dev/sdc1

FYI: I have backups. I understand RAID 1 may be a better choice of raid level.

What you might do to avoid having to "grow" the RAID partitions is to put your md device(s) into LVM. The md will give you the RAID redundancy you want and LVM will give you the flexibility of adding/removing md devices and/or extending/reducing logical volumes without having to deal with partitioning.

You're segueing into my next question... DM (which I'm pretty sure is LVM) doesn't show up well in fdisk as well... Is this normal? Based on the purpose of LVM, I am assuming so.

Thanks,
WT

DM might mean "device mapper" or it might mean "dynamic multipathing".

Since Logical Volume Manager (LVM) logical volumes (LVs) are NOT true disks or partitions fdisk wouldn't be used to see detail about them. Instead you'd use lvdisplay. Most LVs end up with device mapper paths so this may be why you mentioned DM. However the Volume Group (VG) the LVs are in does have what it calls "Physical Volumes" [PVs} which can be whole disks, partitions of disks, meta disks or multipath devices. If you're using partitions or whole disks then fdisk will give you information (for whole disks it will tell you it doesn't contain a valid partition table but will show you the entire size of the disk.) For meta disks or multipath devices you might need to determine the underlying physical disks/partitions that comprise the device and do fdisk on those underlying devices.