What if I do RAID10 using 6 partitions?
___ ___ ___
a |1| |2| |3|
--- --- ---
b |2| |3| |1|
--- --- ---
Make RAID0s out of row a and row b, then raid1 them. I think this is more adaptable than raid 5. I've already worked on paper how to expand that array. Even if I were to add a 2GB drive it's possible to have a RAID10 with full data redundancy. The only thing I dont know about is if partition b2 is going to be identicle to partition a2. If they're not exactly the same it would be a waste, and seeing as how the partitions are slightly different in size, the two RAID0 arrays could be off by a few blocks from each other... Maybe it's better to RAID1 each pair and put those pairs in RAID0...
I've been trying to create a RAID0 out of the top three though just to see how everything works but I've been getting errors.
mdadm --create --verbose -l 0 -n 3 /dev/sdb1 /dev/sdc1 /dev/sdd1
mdadm: You haven't given enough devices (real or missing) to create this array
Then sdb1 errors any time I try to do anything with it; "/dev/sdb1: can't read superblock". I have to reboot to access sdb1 again. sdc1 and sdd1 continue to work just fine.
I also get an md device.
"mount: special device /dev/md127 does not exist"
"mdadm: md device /dev/md127 does not appear to be active."
I dont understand why it doesn't work. I give it three devices, tell it I want to use three devices, then it tells me I didn't give it enough devices to make the array. I'm doing it exactly as I've seen in examples on the web, and these errors show up nowhere.