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mdadm and whole disk array members

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I've spent a few days experimenting with using whole disks in a RAID 5 
array and have come to the conclusion that it simply doesn't work well 
enough to be used.

The main problem I had was that mdadm seems to have problems assembling 
the array when it uses entire disks instead of partitions. Each time I 
restarted my computer, I would have to recreate the array. This causes 
the boot process to halt because /etc/mdadm/mdadm.conf and /etc/fstab 
both identify an array that should be started and mounted. Fortunately 
the create command was still in the bash history so I got the create 
parameters right.

However, after I added another disk to the array, that made the original 
create command obsolete. Plus the kernel assigned different drive 
letters to the drives once I plugged in a new drive, so that I couldn't 
simply add the new drive to the create command.

Fortunately I still had a decade-old script that would cycle through all 
combinations until it found one that would result in a mountable array 
(I had the script due to some problems I was having back in 2010). 
Unfortunately it didn't find any it could mount no matter what the order 
of the drives (which included one "missing").

I've found many other people complaining about similar issues when using 
whole disks to create mdadm RAID arrays. Some of these complaints go 
back many years, so this isn't new.

I suggest that, since it appears the developers can't get this work 
reliably, that the option to use the whole disk be removed and mdadm 
insist on using partitions. At the very least, mdadm --create should 
issue a warning that using a whole device instead of a partition may 
create problems.

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mdadm and whole disk array members Gary Dale <gary@extremeground.com> - 2021-03-22 23:30 +0100
  Re: mdadm and whole disk array members Andy Smith <andy@strugglers.net> - 2021-03-23 00:00 +0100
    Re: mdadm and whole disk array members Gary Dale <gary@extremeground.com> - 2021-03-23 00:50 +0100
      Re: mdadm and whole disk array members deloptes <deloptes@gmail.com> - 2021-03-23 13:40 +0100
        Re: mdadm and whole disk array members deloptes <deloptes@gmail.com> - 2021-03-23 13:50 +0100
          Re: mdadm and whole disk array members Reco <recoverym4n@enotuniq.net> - 2021-03-23 16:50 +0100
            Re: mdadm and whole disk array members Gary Dale <gary@extremeground.com> - 2021-03-26 02:30 +0100
              Re: mdadm and whole disk array members Felix Miata <mrmazda@earthlink.net> - 2021-03-26 05:10 +0100
                Re: mdadm and whole disk array members Gary Dale <gary@extremeground.com> - 2021-03-26 19:10 +0100
              Re: mdadm and whole disk array members deloptes <deloptes@gmail.com> - 2021-03-26 08:00 +0100
                Re: mdadm and whole disk array members Gary Dale <gary@extremeground.com> - 2021-03-26 19:20 +0100
          Re: mdadm and whole disk array members Gary Dale <gary@extremeground.com> - 2021-03-26 02:20 +0100
            Re: mdadm and whole disk array members Gary Dale <gary@extremeground.com> - 2021-03-26 02:30 +0100
        Re: mdadm and whole disk array members Gary Dale <gary@extremeground.com> - 2021-03-26 02:20 +0100
  Re: mdadm and whole disk array members Andy Smith <andy@strugglers.net> - 2021-03-26 17:30 +0100
    Re: mdadm and whole disk array members Gary Dale <gary@extremeground.com> - 2021-03-26 19:40 +0100
      Re: mdadm and whole disk array members Andy Smith <andy@strugglers.net> - 2021-03-26 22:00 +0100

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