Setting up a case with power supply for only HDD's. Is it possible?

[RoccoT]

Hi folks, I'm trying to figure out a solution that simple enough in theory has turned into something way more complicated.
I have a main desktop PC with a new internal RAID card. I've simply run out of space inside my computer for additional hard drives (i'd like to setup 8 drives in raid). What I was hoping was to build another case with just a power supply and run 2 SAS - 4 sata fan out cables from inside the main computer to the Raid case. Since the power supply needs to be attached to a motherboard to turn on, what would be the best option for this? I've seen posts where people are putting jumpers in the main motherboard cable. Or I was thinking of just installing an older motherboard and plugging into that so that when I turn on the computer it starts up the power to all the internal hard drives.

The ideal scenario would be no second motherboard, just the case, power supply and 8 drives. Have the power supply communicate somehow with the main computer and it would power on whenever the other PC powers up.

If you have any suggestions on this please let me know!

Cheers.

 

[Cerb]

If you want something off the shelf, you have to be careful about your hardware choices, and if not running Windows, even more careful. Basically, if you can't find known-working port multipliers for your controller, don't do it, or get controllers known to work. FI, Addonics has SAS/SATA port multipliers for their enclosuers, but I don't know if they'll work with anything but a handful of controller chips.

If you want a start on COTS throw-it-together stuff, begin here:
http://www.addonics.com/category/storage_tower.php

If you want to DIY it on the cheap, and to turn it on and off with the main computer, here's what to do:

1. A good SFF PSU, such as out of a SFF Dell or HP business computer (Optiplex, Precision, Poweredge, Z-series, DC-series), or a new one branded from a good maker, like Seasonic, Delta, Athena, or Zippy. Or, a bigger PSU, if you like. You could also get a 12V bench supply, too. Parts Express and MPJA often have them for about the cost of an aftermarket ATX PSU.

2. Take 12V out of your case (you can get expansion slot brackets for this, if you don't have one), to connect to a relay. This relay will then turn on the power supply. Pictures! If you don't have this stuff laying around, you can get all the needed connectors, wires, and a crimp tool from Walmart and any local auto parts store. If you want to get fancy, you could set up an RC circuit on the switch so it turns off shortly after turning on, too, but I'm pretty sure you won't need that just to give power to some HDDs. If you can solder, then you can forego the crimp tool, and solder-fill the connectors that go to the relay, or solder to the relay directly. A solder connection will be fine.

3. Either nibble a slot cover to let normal SATA cables pass, or get eSATA brackets. eSATA brackets, while the "right way" to do it, will take up 4 slots. If your RAID controller has known support for SATA port mulripliers, you can do this easier, with only 2 eSATA brackets, though you will need to purchase a port multiplier to install in the other case. Alternatively, if you use software RAID, you could replace your controllers with controller known to have such support. If you're going to have it right next to the main computer, then if you use SAS fan-out cables for your controller, you can just route those outside and then into the other case.

4. Find a good enclosure, some 3.5" drive cages (Newegg, Directron, and eBay have plenty to choose from), and go to town.

P.S. Intel and AMD SATA ports apparently support SATA port multipliers in Linux, at least with the RAID-supporting chipsets, but Intel's do not in Windows, and ??? on AMD's in Windows.

 

[RoccoT]

thanks for the tips

I like the idea of having the 2nd psu turn on automatically when the main computer is started. I tried looking up relays and I'm guessing a relay is different from a switch?

If i can make something like this work, can someone point out which cables I should connect to on the ATX connectors? and what's the best way to attach the wires to the connector already on the PC #1 motherboard?

I found these articles here;

http://www.directron.com/2powersupplies.html#atxauto

 

[Cerb]

I like the idea of having the 2nd psu turn on automatically when the main computer is started. I tried looking up relays and I'm guessing a relay is different from a switch?

A relay has contacts that, when closed, physically move an arm, like a solenoid does a rod, with an electromagnetic coil. This typically (latching relays are an exception) switches it from it's off state to its on state. It then has switch contacts. So, with the coil contacts of a 12V relay on +12V and GND, the relay will switch when your PC turns on. You could then use any quality 12V/5V PSU, though standard computer PSUs are more likely to just be hanging around.

Checking out Wikipedia's article on relays, you'll probably want to look somewhere else for more info. Here's something I quickly found:
http://www.instructables.com/id/How-Electronic-Switches-Work-For-Noobs-Relays-and/?ALLSTEPS

If i can make something like this work, can someone point out which cables I should connect to on the ATX connectors? and what's the best way to attach the wires to the connector already on the PC #1 motherboard?

I have 2 eSATA brackets, each of which brings out a standard 4-pin molex connector. You can make a simple male-male jumper from a standard molex extension or splitter cable, just by splicing the wires from two male ends together, which would make for a removable jumper for the 2nd PSU. For it to be switched, you'd want to switch the common from open to closed, and just wire the male pins straight from the PSU leads. You can use thin-tipped needlenose pliers, or very small flathead screwdrivers, to bend in the tabs holding pins inside of the molex connectors.