On Fri, Jan 22, 2010 at 2:34 PM, Robert Howard <rjh0507@ecu.edu> wrote:
RAID5 is one of the levels that can be added to after creation. I think you should boot from the install CD and read the mdadm man page. It contains all the information you need to do what you want. That said, when you try to build the 4-drive array, do you get any errors reported? You may need to set the partition type to Linux MD RAID for the new drive if you intend to use the mdadm hook to assemble the array.
On Jan 22, 2010 1:15 PM, "Dwight Schauer" <dschauer@gmail.com> wrote:
Can you add a drive to an array after it has been built?
I know you can add a hot spare, or remove a drive and add another, but I did not think you could increase N, where the size of the array is N-1 * size of each drive. How is the raid going to know which is data and which is parity?
Of course I could be wrong.
I don't doubt that I could build a working Arch system with 3 physical drives and then use 'mdadm' to add the 4th drive as a spare or as additional disk space for the RAID5 array. I should be able to add a 4th disk to RAID5 w/o having any 'hot spares, correct? I just feel that I should be able to do this from a fresh install. I assumed I was missing a syntax in the command. I partition all 4 disks identical. All disks have a equal amount of partition space assigned to RAID (type = fd) and then I use mdadm to build the array so I can't see why it does not work. Yes I do have a USB keyboard but if I don't need to add the usb modules for RAID5 with 3 disks, why would I need to add it for RAID5 with 4 disks. It makes no sense to me...