> For better performance, more space, and higher throughput, I would
> probably create a RAID 4 or RAID 6 array from the external enclosure
> and use it as the data repository.
And you suggest I put a 4-drive enclosure in my backpack next to my laptop?
Seriously?
>> For the BananaPi, the suggestion is marginally less problematic but
>> still: a non-trivial constraint with significant immediate downsides.
> Such as?
Extra space taken, extra power used 24/7 (which in turn requires an
extra plug because the poor BananaPi can't provide all that power),
extra costs (the single drive I use was itself more than 3/4 the price
of the whole system, so adding a second drive (complete with external
power supply and enclosure) would double the price of the system),
Extra failures (more hardware => more failures), ...
>> RAID is basically an insurance.
> Not entirely. A RAID 5 or RAID 6 array is far, far faster than
> a single hard drive.
Right, RAID-over-USB is of course going to blow my SSD-over-SATA out of
the water by a wide margin (not!).
> It is also much larger than a single hard drive, sometimes at
> less expense than a single large hard drive.
That's great if you happen to be in that spot, but that's not my case.
> It is also portable from one system to another. Unplug the array
> from the laptop, plug it in to the Banana Pi, and presto! The array
> is now attached to the Pi.
Wonderful. But then it's not a RAID shared with the internal drive
any more. So it won't protect my root partition. And if I keep my home
partition in it, the "presto" comes with the footnote "after you logout
and log back in" (fun!), but if I don't keep my home partition on it,
then my home partition is again not protects by RAID at which point I'm
starting to wonder what I would put on that RAID.
> It's really not any different logically than an external drive,
> except it is faster, larger, and more robust.
It's no different, indeed, except a bit more expensive and bigger.
But more importantly: there's a reason why I'm not using an external
drive at all in the first place.
>> Taking an insurance makes a lot of sense when it's important to
>> spread the cost of the impact of an "event"
> Or eliminate it entirely.
If a disk dies in the RAID, you still have to replace it and the
performance is affected for a while. The cost is never
completely eliminated.
>> anyway (not to mention that RAID doesn't prevent me from losing work
>> when the OS or my editor crashes
> Uh, yeah, it can. It definitely can be used to eliminate data loss
> when the OS crashes,
Of course it can't: when the OS crashes, the unsaved work in your editor
is lost. And as for the work that was saved to disk, I wonder in what
way RAID can improve the situation compared to a single disk (in both
cases, I expect that the data will not be lost).
> That is another matter. Indeed, it is probably the most likely
> reason a need for a backup solution exists.
For my use-case, RAID would cost a fair bit of money and inconvenience,
and the benefit would be rare and minor.
I suspect your "world" is one where you have U1 blades and things like
that and/or where the disk's content is not 100% your own (i.e. other
people depend on it), so for your use case RAID is probably
a no-brainer. For me, the choice is similarly blindingly obvious but
diametrically opposed because my use case is radically different.
Stefan
