I have three drives in my current system (all 1TB). The current setup is:
sdb - raid0 member (failing soon)
sdd - raid0 member
sde - backup
I'd like to change it so all three drives are part of a raid 1e (mdadm raid 10,n2) my main concern now is reliability, with space second, and speed as an appreciated bonus.
Looking at this manual I see I can create a "degraded" array (in this instance, with sdb and sdd) and copy the data onto it, and then add the third drive. It doesn't say anything about complex raid10 modes though. Data-wise raid 10n2 expecting 3 drives can exist with only 2, although I'm wondering if mdadm won't let me actually build and use a 10n2 array with a missing drive.
Best Answer
I tried it with
and it seemed to work.
Since it operated in degraded mode I can assume data is mirrored, and array device size is 150% the size of a drive as expected.