Partition RAID or multiple RAIDs per partitions

Question

I'm trying to setup a RAID 1 with two HDDs. This is what I'm trying to achieve:

• data partition (ext4)
• Mac TimeMachine backup partition (HFS+)

I want to have RAID over both partitions, but I still want to be able to pull one of the drives and connect to the Mac via SATA/USB and use the HFS+ partition to be able to use the backup directly without needing the NAS. Furthermore, if one drive fails it should be "easily" replaceable, I probably just need to find another drive and create the same sized partitions again (which should be fairly easy?).

Is it advisable to create two separate partitions on the physical drive, one ext4 and one HFS+ and then create two separate RAIDs? Are there any downsides to this?

Thanks!

Answer 1

There's only one sensible option here - one RAID containing multiple partitions.

Answer 2

If you've only got 2 disks, 2 seperate RAIDs is pointless (if even possible) because if one disk dies you lose the mirror of both 'slices'.

If I understand correctly you also want to be able to take one drive out to plug it in to something directly? I'm not sure how well that will work - RAID 1 isn't designed to have drives pulled like that, and it might do something like mark the drive as 'failed' and then try to rebuild it when it returns - it probably wouldn't merge the changes in to the other drive.

I think if you want to do this you're better off having an external drive that you use, and maybe taking a backup of that onto your NAS perhaps by plugging it into the NAS device?

In short, I'm not sure what you want to do is possible!