Greg's Tech blog

Amahi, Fedora & RAID

Sunday 28 of November, 2010

I've recently taken the plunge to convert most of the server duties for my network into an Amahi digital home assistant (cache). The Amahi product is superb and has matured quickly over the past 12-18 months. I had some interesting issues getting started, maybe this will help you.

Amahi is currently built over top Fedora 12. When I built my server, I had two drives in it, 1 ATA & 1 SATA. During the initial install, Fedora built a LVM with the two drives. Knowing I wanted to make use of the drive pooling feature (greyhole, don't ask), I removed the disk from the LVM and got started.

Fedora put /boot and / onto the ATA drive and the system installed fine. Once I had it running, I added a second SATA disk so now I had two 250GB SATA disks I planned to add to the pool. Problem was, I couldn't get a file system on the second SATA disk. I could run cfdisk to delete and create partitions, but when I tried to use mkfs to format the disk, I got an error saying the disk was busy.
I discovered two issues. The first was one of the SATA drives was disabled in bios (Dell Optiplex GX620). Its not clear if this caused an issue, because I was able to access the drives from within the OS

Second issue was Fedora was adding the disks to a RAID group automatically. I'm just starting to understand this, but I used mdadm to remove the disk from the raid group. (Use cat /proc/mdstat to see the name of the devices.) I then used mdadm -zero-superblock /dev/... to prevent the disks from being detected as part of a raid group.