From the mdadm man page:
"When creating a RAID5 array, mdadm will automatically create a degraded array with an extra spare drive. This is because building the spare into a degraded array is in general faster than resyncing the parity on a non-degraded, but not clean, array. This feature can be overridden with the --force option."
So I have 4 hard drives I'm going to want to drop into an array... The howto I'm using specifies to use one of them as the 'spare'...
AKA:
mdadm --create --verbose /dev/md0 --level=5 --raid-devices=3 /dev/sdb1 /dev/sdc1 /dev/sdd1 --spare-devices=1 /dev/sde1
What I don't understand is why this occurs, my assumption is that I would end up with a 3 drive array and a hot spare... What if I don't want that and I want a 4 drive array, I see that I can do that with the -force option...
I'm just wondering why this is the default and if I'm missing anything...
Thanks in advance.