SATA Power to trigger Optoisolator for parallel PSU

Thread Starter

ballardian

Joined Dec 26, 2020
6
Hi all,

Long story short my embedded computer motherboard that only runs off of 12v doesn't have enough power to run the number of SATA drives/devices I want to. Or at least not comfortably safely for me. My goal is 4x 2.5" drives which on average pull 1-2A on 5V on boot. Ideally, the motherboard mfgr will get back to me with the max current I can pull from the 5V rail from the onboard SATA power connecter/DC distribution board BUT if they don't or it is to small I'm looking at alternate options.

Right now this is my plan:

12V into the case -> Split -> 1/2 to the motherboard & 2/2 to a picoPSU where I can hook up the SATA drives. The kicker is I want the SATA drives to power down when the board goes to sleep or is off as it will spend over 95% of the time in sleep mode -- no reason to wear and tear the drives.

What I want to do is take the 5v rail from the onboard SATA connector run it through an optoisolator and have it switch the ATX 'soft power' pin on the picoPSU. So once SATA power comes on the optoisolator acts as a tiny relay and brings the picoPSU up and when SATA power goes off it brings the picoPSU down too. That will ensure the SATA drives are ready for the rest of the computer when needed and there isn't a timing delay with either the detection circuit or method and are also off in lock step when they aren't needed. It seems relatively elegant.

My question is do I need anything more in my circuit to make this happen? On the SATA side it needs to run the optoisolator LED so I assume a small current limiting resistor is a good idea? I'm also planning to run on HDD on the SATA line directly to make sure enough current is being used. On the picoPSU side all the testers are just a wire jumper shorted 100% so I can't imagine I need anything on that side?

But I'm curious what others think? Honestly, it seems to simple and elegant to be safe and correct. So I'm asking here.

I haven't taped into SATA power before and really don't want to fry the one power connector on my board or even worse -- the entire board and embedded processor with it.
 

LowQCab

Joined Nov 6, 2012
123
No ....... "Simple and Elegant" is installing a single "Solid-State-Drive" (SSD) which doesn't have a Motor !!!
They are more Reliable,
they use ~1/10th of the Power,
they don't make any Noise,
they produce very little Heat,
they are physically more Compact, and Lighter in Weight,
they are anywhere from ~5 -to- ~20 times FASTER !!!!!!! ,
they are not affected by Shock or Vibration,
they are quickly becoming Cheaper than Mechanical Drives,
Check with your local Computer Repair Shop for a used one.
.
.
 

Thread Starter

ballardian

Joined Dec 26, 2020
6
No ....... "Simple and Elegant" is installing a single "Solid-State-Drive" (SSD) which doesn't have a Motor !!!
They are more Reliable,
they use ~1/10th of the Power,
they don't make any Noise,
they produce very little Heat,
they are physically more Compact, and Lighter in Weight,
they are anywhere from ~5 -to- ~20 times FASTER !!!!!!! ,
they are not affected by Shock or Vibration,
they are quickly becoming Cheaper than Mechanical Drives,
Check with your local Computer Repair Shop for a used one.
.
.
I agree that is a much more elegant solution. However, 3x 4TB SSD's aren't in my budget right now. Or else I would be using them.
 

LowQCab

Joined Nov 6, 2012
123
If you need 3- 4-Terabyte Drives you're not a hobbyist, and who ever you work for CAN afford it.
But you probably don't need that much space in any case.
Time to clean-out the junk .
 

Thread Starter

ballardian

Joined Dec 26, 2020
6
If you need 3- 4-Terabyte Drives you're not a hobbyist, and who ever you work for CAN afford it.
But you probably don't need that much space in any case.
Time to clean-out the junk .
I am a hobbyist in this capacity. And you are also right I don't need that space right now but I'm building out a new mini server that servers as both redundant storage and backup of machines in my house. As such I'm building out a machine that I hope will last another 10 years like my old server. BUT I made a mistake spec'ing out the psu with motherboard. So I'm trying to get one more SATA power that goes on and off with the board.

Realistically, what I need right now is 2x 2TB SSDs which are also out of my price range but I also need some room to grow into 4 drives if I need them.
 

LowQCab

Joined Nov 6, 2012
123
Just 1 Terabyte is an absolutely SICK amount of Data,
it would take a day and a half just to De-Frag one Old-Skool Motorized Hard-Dive at that size,
and if you're running an Internet Server, they are just too slow and clunky to mess around with,
especially when SSDs are getting almost as fast as your RAM.
If you're running a Server, you should getting Paid to run a Server, it can be a substantial Job.
Unless you are a Hobbyist, and you're just doing it because you can, and for bragging-rights.
Motorized Hard-Drives are now only for Automated-Back-Ups, just in case.

It might be an Idea to simply get a Drive-Box/Frame with it's own Power Supply,
it will still be SATA connected.
 

Thread Starter

ballardian

Joined Dec 26, 2020
6
Just 1 Terabyte is an absolutely SICK amount of Data,
it would take a day and a half just to De-Frag one Old-Skool Motorized Hard-Dive at that size,
and if you're running an Internet Server, they are just too slow and clunky to mess around with,
especially when SSDs are getting almost as fast as your RAM.
If you're running a Server, you should getting Paid to run a Server, it can be a substantial Job.
Unless you are a Hobbyist, and you're just doing it because you can, and for bragging-rights.
Motorized Hard-Drives are now only for Automated-Back-Ups, just in case.

It might be an Idea to simply get a Drive-Box/Frame with it's own Power Supply,
it will still be SATA connected.
1 TB is a lot of data but depending on what the medium is it isn't that much 'useable data'. My project is hobby oriented but in my day job I work assisting with servers and support the users who need storage. Our video editors generator 1 TB of data VERY quickly comparted to days of yore. In those cases between local scratch disk, working storage, final storage, and backups -- there is a small amount of SSD storage vs spinning disk simply due to cost. Our photographer also generators large amount of data though not at the same rate as videos.

My use some of the 1 TB is good backups on multiple computers in the house. Doing incremental with full back ups periodically. As well as some large storage/backups of SD card for projects that are 1:1 images for them -- that is 32 GB at a time. Much of that use is deeper archive and as you stated -- is perfect for spinning disks. This project is part of a bigger backup scheme I run in my world besides primary file storage. So 1 TB is a lot esp compared to 10 years ago but it isn't hard to need 1-2 TB as a pretty typical user -- even just cell phone photos add up.

I could easily get an external storage unit with it's own PSU. That would be easy it is true though part of this project is lowest power possible -- of which surprisingly 2.5" spinning disks are about the same draw as SSDs (ignoring the startup current). I also wanted the power to drop when the computer goes to sleep -- hence trying to use the SATA power as a trigger to the 2nd psu. In this scenario the drives would shutdown / use no power just as if they were natively connected via SATA.

This server is definitely not internet facing either. That is solidly on purpose.
 

Thread Starter

ballardian

Joined Dec 26, 2020
6
The manufacturer got back to me with the specs of the 5V rail on the SATA power connection on the board. Thankfully, it is enough for me to work with so I don't need to use the 2nd PSU. Whew.

I can run 2x SSD + 1x 2.5" HDD or 3x SSDs with no problem. 2x HDDs is CLOSE to the limit but probably safe. The board will have 3x SATA ports so this is enough growth room for me.

Thanks for the folks that responded and I still am curious about this from a circuit perspective -- whether or not I run a relay, solid state relay, or optoisolator --is both sides of the circuit as simple as I think it is.
 
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