Hi all,
initially, I had the impression that SnapRAID (by itself) worked similar to UnRAID or ZFS in that it pooled drives (mixed size drives possible) into one or more virtual volumes, managed the drives configuration, calculated parity and enabled some kind of resilvering (restore). Their website isn't totally clear on that.
But then I noticed that SnapRAID always (?) came up in conjunction with some software like mergerfs or DrivePool. This seems to indicate that SnapRAID itself does not do any drive pooling.
However, I don't understand how SnapRAID could do the parity calculation and resilvering (restore) operations without knowledge about the pool. The way I understand other mixed-drive RAIDs like Drobo's BeyondRAID or Synology's SHR work is that they calculate multiple (partial) RAID arrays according to the number and size of drives and combine them (with mirroring thrown in for the remaining two-drive parts) into one (virtual) array.
Or maybe SnapRAID only works on the physical drives layer, and leaves the pooling stuff to some kind of volume manager? I don't quite get how this could possibly work.
I'm pretty confused, can someone add some clarity?