I'm using Dell Precision T3610 towers as Linux servers for various applications. These have Intel "Rapid Storage Technology" controllers onboard, with a rudimentary RAID functionality, commonly referred to as FakeRAID.
My ultimate goal here is to have backup drives I can just pop in if a drive fails in an existing server. I made a copy of the live server's drive (it only has 1) using dd, which worked fine. Then I put 2 blank disks in a new T3610, configured the onboard RAID controller for raid1, and booted from a CD. I created the partitions on the raid array (md126) to be roughly the same size as the source drive, and connected it via USB. I then used dd to copy the data from the bare drive into the array's partitions. Once completed, I mounted the array, chrooted into it, and ran grub2-mkconfig and grub2-install.
Note: grub2-install complained about having no BIOS boot partition (these disks use gpt partition tables), but the source disk doesn't have one either, and definitely had GRUB installed. grub2-install --force worked fine.
I pulled the USB-connected source disk, and the liveCD, and rebooted the system. It booted fine. Its drives looked like:
# ls /dev/?d*
/dev/cdrom /dev/md125 /dev/md126 /dev/md126p1 /dev/md126p2 /dev/md127 /dev/sda /dev/sdb
/dev/fd:
0 1 2 3
I think shut down the system (cleanly), pulled the drives, and placed them in another T3610 (all hardware identical). First I loaded the onboard RAID config utility, which automatically saw the RAID1 array (complete with the name I assigned it at create time, "ARRAY0"). Thinking this was a good sign, I exited without making any changes. The system booted.
However, Linux did not see the RAID array. It appears to be booting off of only 1 drive. The drives now look like this:
# ls /dev/?d*
/dev/cdrom /dev/md125 /dev/sda /dev/sda1 /dev/sda2 /dev/sdb
/dev/fd:
0 1 2 3
md125 is the imsm container, which shows the same as it did before.
I can provide pictures showing the two controller config screens seeing the array, or any command output. I'm more-or-less confident I've set this up right (as "right" as it can be when using fakeraid), but I'm running into some quirk or shortcoming involving moving an array from one system to another.
Any idea why this second system won't see the RAID array? Even though the controller does?
Thank you all.