Recreating RAID1 after the reckless mdadm usage

["Artem S. Tashkinov" <birdie@permonline.ru>]

Hello,

I have initially created RAID1 in a wrong way:

mdadm --create --verbose /dev/md0 --level=1 --force --raid-devices=1 
/dev/sda1

Note the --raid-devices=1 option and nowhere to be found 'missing' argument.

People have told me I wouldn't be able to add another partition to have 
a working RAID1. Unfortunately, I've already populated /dev/md0 with a 
great deal of data.

Then I did this:

mdadm --stop /dev/md0
mdadm --create --assume-clean --verbose /dev/md0 --level=1 --force 
--raid-devices=2 /dev/sda1 missing (which is obviously the right command).

After doing that I see that my data on a recreated /dev/md0 is there (It 
seems like it's intact). Is it safe to use this RAID1 and is my data 
safe? Can I now add the second block device to md0 using 'mdadm /dev/md0 
-a /dev/sdb1' command?

With respect,

Artem S. Tashkinov