[Discuss] NAS: lots of bays vs. lots of boxes

[tmetro+blu at gmail.com (Tom Metro)]

Derek Atkins wrote:
> I plan to build a freenas box.  I can get a 24-bay 4U case and build
> into it for about the same price as a synology...

That's fine if you need lots of drives to achieve your capacity
requirements in the bear term. If you do, the DIY approach is very
appealing, as you can accommodate a lot of spindles for a small
incremental cost.

I've gone down that path as a thought experiment. Having the ability to
handle lots of drives gives you the comforting feeling that you can
always expand capacity easily by adding another drive.

But the reality is that you only need to be able to expand capacity at a
rate faster than your needs are growing, and for lots of use cases the
rate at which the industry increases density per dive outpaces this. If
not, then add a couple more drive bays, and repeat the math until your
overall array shows a predicted capacity increase from drive density
than your predicted need.

A box with 24-bays is going to be rather expensive if your short term
needs are for only 4 or 6 bays. Unless a high percentage of those are
for "near line" backup storage, you need to support those bays with more
RAM, more SATA ports, faster CPU, more Ethernet ports, etc.

And then you've got an expensive box with a ton of storage and a single
point of failure.

I'm more interested in clever ways of using multiple, cheap, commodity
NAS boxes, Google-style. For example, for the same cost as that $600+
(diskless) DIY NAS I linked to, I can get 4 of the QNAP 2-bay boxes and
maybe combine them with something like MooseFS. You get redundancy where
some number of the boxes can go down, and it still keeps working, and
you can expand capacity by adding more boxes (if drive density increases
don't keep pace).

 -Tom

-- 
Tom Metro
The Perl Shop, Newton, MA, USA
"Predictable On-demand Perl Consulting."
http://www.theperlshop.com/