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jobr

join:2004-10-21
Halifax, NS

Powering 2.5 inch SATA drives

Hi. I'm planning a little project for making a small/low-power home NAS that involves connecting four or five 2.5 inch drives to a SATA port multiplier, which in turn would be connected to an ARM SoC. But I'm not sure what would be the best way of powering the drives. I've thought of two options:

1. Use SATA 15-pin->Molex adapters, and connect those to a cheap ATX power supply.

2. Use (or make, since they don't seem to be readily available) SATA 15 pin->USB adapters, and connect to a multiple-port USB charger.

Option 1 seems like overkill, and I don't really want to use a big and potentially noisy power supply.

Option 2 seems better, but for five drives I'd need more than one charger.

Is there a better option? Ideally, I'd like a power brick with five molex connectors but I haven't been able to find that.


Tirael
BOHICA
Premium
join:2009-03-18
Sacramento, CA
kudos:2
Is this going into some kind of case? If so, a cheaper ATX power supply should do the trick. I would suggest this Seasonic 350W 80+ Gold PSU.

It should make that much noise. However, if you want something smaller, you might want to look at an SFX PSU. They are about 1/3 the size of a standard ATX PSU. I have one from Silverstone (ST45SF) and there is a Gold version of that PSU as well (ST45SF-G).

You would have to make the SATA to USB adapters yourself (the only thing I know of is eSATA to SATA power) which just seems ridiculous.

Of course, your "ideal" would be pretty easy to do. Get a few of these, a few of these, and as many of these as you need. That should do what you want.
--
“Reality doesn't bite, rather our perception of reality bites.” - Anthony J. D'Angelo
»www.chaoticconfused.com


koitsu
Premium,MVM
join:2002-07-16
Mountain View, CA
kudos:23
reply to jobr
I would recommend option #1 and strongly recommend against option #2 (the voltage coming across a USB port is going to fluctuate a lot more than what comes directly out of a PSU, and you then also become susceptible to any kind of chipset oddities where the chipset ends up ceasing flow of power to the +5V line -- some do control this! It's not a blind passthrough!).

Me personally, I'd go with option #3 -- if you're building this NAS, then get yourself a PSU that has native SATA power connectors on it (no need for Molex adapters -- I hate those things anyway).

Or alternately, get yourself a decent NAS chassis that has a hot-swap backplane in it so the drives are natively connected via SATA; many of these backplanes have one or two 4-pin Molex connectors on them.

The Seasonic PSU linked earlier includes native SATA power cabling for up to 4 drives, from what I can tell. If you went with 5 drives you would need to use one Molex adapter.

Footnote: I will warn you in advice: port multipliers have a whole series of bizarre behaviours, many of which are driver-level. The exact SATA chip being used with PMP plays a huge role here. I can point you to real-world fixes for these type of things in server-class OSes (ex. FreeBSD) if you think I'm kidding. The general recommendation is: try to avoid PMP if at all possible. This isn't even touching on the bandwidth/performance aspect of PMP (4 drives being accessed will certainly saturate a SATA300 port, and very possibly a SATA600 port).
--
Making life hard for others since 1977.
I speak for myself and not my employer/affiliates of my employer.

jobr

join:2004-10-21
Halifax, NS
reply to jobr
Thank you for the advice! The intention is that this would go into some kind of case, so I'll try the ATX power supply. The power brick in the link only gives 5 V / 2 A, which is probably not enough to power five drives.


Tirael
BOHICA
Premium
join:2009-03-18
Sacramento, CA
kudos:2
said by jobr:

The power brick in the link only gives 5 V / 2 A, which is probably not enough to power five drives.

You would need three of them (hence why I said "get a few").
--
“Reality doesn't bite, rather our perception of reality bites.” - Anthony J. D'Angelo
»www.chaoticconfused.com


aurgathor

join:2002-12-01
Lynnwood, WA
kudos:1
Reviews:
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reply to koitsu
said by koitsu:

Me personally, I'd go with option #3 -- if you're building this NAS, then get yourself a PSU that has native SATA power connectors on it (no need for Molex adapters -- I hate those things anyway).

Another reason for a native SATA PWR connector is the presence of 3.3V. While mechanical HDs don't usually need it, there are some mSATA SSDs that will not work when used with a molex to SATA adapter because they use +3.3V instead of +5V.
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