[mythtv-users] Another take on large-capacity disk enclosures

f-myth-users at media.mit.edu f-myth-users at media.mit.edu
Mon Jun 15 21:23:32 UTC 2009

Steve Adeff's message of last week got me looking around, and I've
come across a solution that might be good for people who need up to
20 disks cheaply (as we might soon for an ongoing project):

1x NORCO RPC-4020 4U Rackmount Server Case ($289)

2x SUPERMICRO AOC-SAT2-MV8 64-bit PCI-X133MHz SATA Controller Card ($99)

At ~US$528 (shipped), this is certainly more expensive than the TR8M-B
8-disk (+eSATA) enclosure, but OTOH, if you need more than 8 disks or
need to build a new machine as a NAS -anyway-, it's probably more
compact and cheaper overall.  My idea here is to buy 1 Norco and
two Supermicros, along with a motherboard that has at least 2 PCI
-or- PCI-X slots (the Supermicro apparently can be plugged into
either, albeit at a performance penalty for PCI) and has at least
4 additional SATA ports built-in (should be pretty much everything).

This should allow 20 disks (and some reviewers have claimed 24 if you
get crafty and wedge them in in nonstandard places).  The Supermicro
appears to be at least pseudo-hot-swap (e.g., deactivate the disk in
software and then pull it), and the bays aren't claimed to be super-
beefy, but if you're not planning on swapping drives in and out all
the time (I'm not), it seems reasonable, or so imply the reviews.

The plan is to use the disks as a JBOD (and in fact most of them will
be sleeping most of the time, so the two cards' performance with many
disks active should be irrelevant, and means that, while a power
supply that can handle the peak is advisable, it will be quite
unloaded most of the time [are 80+'s still efficient with such low
loads?  haven't checked recently]---I'd rather not get fancy with
multiple power supplies and something to switch 'em on/off).  I'm
also thinking that, unless the NAS mobo gets other duties, it might
spend most of its time with its CPU throttled (and -maybe- sleeping
if the stars align and that's reliable and fast to resume).

Pricing breakdown:  The TR8M-B works out to $35/disk if you get it
while it's still on sale (e.g., today), or $45/disk if you don't.
Obviously you'll need a machine nearby you can plug it into.

The Norco/Supermicro works out to $26.40/disk.  If you're really
getting 20 disks (and let's ignore the fact that 20 div 8 has a
nonzero remainder---or turn around and say you could jam 24 disks
into the Norco if you're clever), then that gives you 20 * $18.60
or $372 (if you don't order the TR8M-8 today) to play around with
for motherboard, power supply, cables, etc.  (I'm not planning
on actually putting this in a rack, so I won't need rails.)

It may work out that the Norco/Supermicro is about the same price
per disk once you roll in all the other stuff, but you get another
computer out of it (may or may not be a good thing) and potentially
a lot more compact (very good in my book)---one 4U rackmount instead
of a desktop and 2-3 of the TR8M's.  And you can put it anywhere you
can get to with Ethernet.


P.S.  The real plan here is probably to clone the order above & keep
the other one in a different physical location.  I'm not so concerned
about seamless recovery from a single disk failure; I'm -quite-
concerned about losing an entire enormous RAID due to
  power supply run amok
  someone tips the case over (*)
  rm -rf OOPS!
  cfdisk OOPS!
etc and will feel much happier with a rarely-on offsite clone that
only gets talked to (or even powered on) when rsync wants to stuff
more data into it from the primary.  This starts arguing for the
Norco's 'cause the clone needs to be its own computer -anyway-...

(*)  (Happened!  I mentioned the fire/flood/theft thing to someone on
some list years ago who pshawed 'em---and then lost his entire raid a
week later when a roommate accidentally kicked over the machine.  Oops.)

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