I have a machine that supports 4 S-ATA drives. I have all identical drives in each slot. I am asking for someone to please tell me how I can create a RAID5 array on Linux and then also have the 4th drive (/dev/sdd) as a hot spare for any of the three drives in the array / volume? I did the following: /device = type @ parition size /dev/sda1 = fd @ 100 MB (bootable for /boot) /dev/sda2 = fd @ 1 GB (Going to be used for Swap) /dev/sda3 = fd @ 300 GB (Going to be used for /) Now I make the same thing for /dev/sdb & /dev/sdc. I DON'T PARTITION OR FORMAT /dev/sdd. Now I am creating my RAID and this is where I am confused. How do I correctly issue the 'mdadm' command to create the volumes for my filesystem and also utilize /dev/sdd as a hot spare? (/boot) Code: mdadm --create /dev/md0 --level=1 --raid-devices=3 /dev/sda1 /dev/sdb1 /dev/sdc1 --spare-devices=1 /dev/sdd (Swap) Code: mdadm --create /dev/md1 --level=1 --raid-devices=3 /dev/sda2 /dev/sdb2 /dev/sdc2 --spare-devices=1 /dev/sdd (/) Code: mdadm --create /dev/md2 --level=5 --raid-devices=3 /dev/sda3 /dev/sdb3 /dev/sdc3 --spare-devices=1 /dev/sdd Is that correct above or would I 1st have to partition the /dev/sdd drive?