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

Graham Mitchell gmitch at woodlea.com
Mon Jun 15 23:24:58 UTC 2009

> If you pick your hardware right, you can get by much cheaper with esata +
> port multipliers at little to no performance penalty, especially if you
> design the wiring so that drives on the same port multiplier are in
> different logical groups.  Port multipliers come in 1x5 versions, so 4
> esata ports == 20 drives.  See the sata maillist for hardware that works.

I used these as the 2 PCIe cards in my server 


You can get them cheaper, but I wanted a single stop solution for myself.
You need to make sure that any SATA card you get is port multiplier ready,
which the Sil 3132 chips are.

For the port multipliers, I used these


(I also used a couple of bridge boards
(http://www.addonics.com/products/multilane/connector.asp) to connect the
server processor box to the external disk box. I would stongly recommend NOT
doing that... just use eSata cables and be done - the Infiniband cable
(http://www.addonics.com/products/other/default.asp#ml) was the single most
expensive component, and to be honest, wasn't worth it).

My setup is an E2180 at 2GHz, with 4GB RAM. I have 2 of the PCIe cards in my
server. The 4 channels on the 2 cards are connected to the 4 ports on the
bridge board (even tho I only use 3). The infiniband cable connects the
processor box to another bridge board in the disk box. I then connect 3 of
the ports to one of the 1to5 port multipliers, which then connect to the
drives. I'm using a Thermaltake M9 case to house the drives, with a 450W
PSU. I've also got the 15 drives mounted in 5to3 drive bays, with a 120mm
fan blowing air over them to keep cool.

I'm using software RAID on it, and performance isn't too bad at 108MB/s, tho
it could be faster. It's all a single md drive, with a single ext3
filesystem on it (worst of both worlds), but it's working well enough for me
at the moment to be not that bothered about it - it's on my list to look at,
but it's fairly far down.

I've been looking at some LSI RAID cards, but I'm not getting that much
extra speed with them, so I am not sure that it's worth loosing the
flexability of the software RAID for the small gain in speed.

> A single moderate PS will easily handle 20 drives; that's only 200W load
> max.  Even at startup, you're only talking maybe 300W to spin up all the
> drives.
> --Yan
[Graham Mitchell] 

Agreed. I have a 450W power supply running 15 x 500GB drives (Hitachi and
WD), and I've got no power issues. I've not looked at the UPS it's connected
to for a while, so I'm not sure of the load that it's pulling, but it's not
that much.

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