I have the following computer landscape at home:

1x Ubuntu machine
2x OSX machines

I want to achieve the most harmonious:

a) file sharing solution
b) backup solution

I have identified HFS+ (unjournaled) as a good file system to use to share files between the two operating systems. I am currently testing a HDD being shared by both systems with read/write capabilities from both.

For backups at the moment it's quite chaotic, the OSX machines backup to a dedicated HDD.

The Ubuntu machine backsup to a different dedicated HDD.

I am torn between two set-ups:

a) 1 HDD using HFS+ to share files between all systems. 1 HDD per system for dedicated backups (i.e. 3 HDDs for backups).


b) Set up a 4th machine. An old laptop running Ubuntu, to which I attach several HDDS and this then serves as a NAS for file sharing and backups over the network.

I cannot decide which option makes more sense. I think option b) would be the least stressful method, but any drawbacks to it?