I'm considering building a storage solution where I would create one large LVM volume out of two or more pairs of disks, each pair running in RAID1. As far as I understand, this would let me expand the volume with more RAID1 pairs later on, and would allow one disk in each pair to fail simultaneously without any data being lost. However, should both disks in one pair fail at the same time, the whole volume will be lost.
Is this a bad idea, as far as reliability is concerned? The main increase in risk that I can see is that in the unlikely event that both disks in one pair fail at the same time, all data is lost, including data stored on other disk pairs. Are there other, more subtle, risks?