0

I am planning to set up a home NAS. I plan to start it with two identical disks in something similar to RAID-1, but Iʼm thinking about how to make sure I leave my options open for growing it later.

First, my starting assumptions. Iʼm not 100% sure of these; please correct me if they are knowably wrong.

  • BTRFSʼs RAID1, RAID10, RAID1C3, and RAID1C4 profiles are stable and reliable.
  • BTRFSʼs RAID5 and RAID6 profiles, although they are not as bad as they were a few years ago, are still not stable and reliable. I expect that they will be in the future, maybe even by the time I might care about them, but I will plan as if they never will be.
  • Assuming there is enough free disk space (where the definition of “free” is different for BTRFS and mdadm, because they see things at filesystem level vs. block level), it is possible to migrate between BTRFS profiles or between mdadm RAID levels, although the array might not be safe from single-disk failures while this is happening.
  • For the special case of two disks in either BTRFS RAID1 or true RAID-1, it’s possible to migrate to the other, by converting one of the disks into a standalone device and then creating the other scheme. This is more of a pain than I thought, with mdadm RAID, but should be possible in both directions as long as there is some free space.

My question is, assuming there is enough free disk space, how easy is it to migrate between mdadm RAID and BTRFS profiles, assuming there is enough space? For example, if I have three identical disks in a BTRFS RAID1 profile (which, unlike true RAID-1, does not mean three mirrors of the same data; it allows recovery with only N-1 disks), can I migrate that to a true mdadm RAID-5?

Improve this question

0

Reset to default

You must log in to answer this question.

Browse other questions tagged .