Built software raid from whole devices instead of partitions: problem?
I set up a software RAID5 with mdadm, which is working fine. I'm using external 500GB USB drives for this.
When I tried to add a spare disk just now I noticed that I didn't assemble the RAID array using partitions on the drives (sda1, sdb1, sdc1) but the whole devices instead (sda, sdb, sdc). Adding the new drive's partition (sdd1) didn't work, because there wouldn't be enough space. Adding the whole device (-a /dev/sdd) worked.
Could this be causing a problem? It's all working fine, but this would be the most convenient time to back up the data to another drive and start over. So if there is any benefit in doing so at all I would really like to know and get it over with.