你说的是不同level的备份。就像所有复杂问题永远没有silver bullet.
我认为raid的好处:
- 速度提升
- 数据备份(I overload this term,but you know what i mean). The assumption
of raid is "the disk failure is random." It does decrease the rate of losing
data a lot. Personally I never saw a disk failure. So I cannot comment on
the probability of the situation you describe.
But raid cannot solve the problem of the single point failure. If the nas
box fall to ground, probably all the disks are gone. As you said, it's
important to keep at least one copy of data in a different location, if they
are really important.
Except of raid0, raid keeps your data safer than jbod. The question is if
you want to pay for that?