Martin5000

Powering a large number of drives

Recommended Posts

I've got 20 drives in my file server. I have alot of problems with drives losing power and crashing explorer or freezing/crashing the computer (the drives click and spin up again).

I have a 520W PSU powering motherboard and 10 drives and a 300W PSU to run the last 10 drives. My problem, I think, is the "y-cables" (1 molex connector -> 2 molex). Apparantly I haven't been able to fine any that have good connections.

What I want to know is how all of you with more drives than the PSU has connectors for have done? Are there any secret PSUs with eg 12 molex plugs or more that I just haven't heard of?

Do you have any recommendations as to how I can improve stability of my system? And by the way, I have thought about moving some disks to another computer, but the absolutely last option. I wont like having to turn on more computers just to access my files.

Share this post


Link to post
Share on other sites

Thanx, but I think my two PSUs are enough to power the drives - my problem is the power cables :-)

The site you linked to estimates I need ~780W to run my system (or 810W to allow future upgrades. I have 820W in total.

Share this post


Link to post
Share on other sites

Going strictly by wattage is a bit naive. Many power supplies have limits on how much they put out on each rail (+12,+5,+3.33, etc.). Added together you get the wattage rating, but each line delivers less.

I believe all hard drives get their juice off the +12V rail. So, what you really need to be sure of is that your power supply(s) provide enough amps on that rail to power things.

I was going to give you a nice example using a popular Antec power supply, but those damn morons insist on setting a cookie before you can even enter their site.

Share this post


Link to post
Share on other sites
Thanx, but I think my two PSUs are enough to power the drives - my problem is the power cables :-)

If you think cables are the problem, then make your own. Jameco and Digikey stock everything you need:

1) molex connector housings

2) male/female pins

3) Good think wire (#14 or #16)

4) a crimping tool if you're making alot of them

5) solder iron (yes I solder my pins in addition to crimping)

6) a pin extraction tool

It's a very simple process, and you can make all the cables you need in one day. You can also make 3-way, 4-way adapters or more. If your situation is extreme enough, I'd recommend making a power bus out of some scrap perf board instead of using an endless series of splitters.

If you're new to all this, check out some case modding sites. They have tons of tutorials for this stuff.

Also, make sure you're not daisy chaining your sliptters ("Y adapters"). If you're using alot of them, make sure you have a nice even distribution so that all paths from the drives to the power supply are roughly the same length (or rather pass through the same number of splitters).

Share this post


Link to post
Share on other sites

I always use connectors from ancient XT power supplies. They are regular molex connectors that just slide onto (and slice into) your power leads. A very secure solderless connection, and you can custom place them wherever you want on your leads if they are long enough to reach the last drive. I don't know where you'd get them new since I always pull them off of dead supplies. I probably wouldn't power more than five drives from each lead though, to keep the load under 5-6 amps per 18 gauge wire. And I don't know of any drive that'll run without the 5v line hooked up.

If you already have the Y-connectors you can always cut and solder them for a solid connection.

Share this post


Link to post
Share on other sites

Make sure all drives are sufficiently cooled (use powerful fans, especially on the exhaust side). Running so many drives plus 24/7, you will need that although this means it will be noisier of course!

You may want try using "ferrite beads" or "suppression cores" on each of the PSU cables leading to each drive and fan used. These stabilise and filter out any unwanted signals introduced by each other devices (drives, fans, motherboeard, etc) on the PSU lines...

What PSUs are you using anyway? :ph34r:

Cheers :rolleyes:

Share this post


Link to post
Share on other sites
Going strictly by wattage is a bit naive.  Many power supplies have limits on how much they put out on each rail (+12,+5,+3.33, etc.).  Added together you get the wattage rating, but each line delivers less.

I believe all hard drives get their juice off the +12V rail.  So, what you really need to be sure of is that your power supply(s) provide enough amps on that rail to power things.

I was going to give you a nice example using a popular Antec power supply, but those damn morons insist on setting a cookie before you can even enter their site.

199660[/snapback]

Zark has the right idea here. Without know which power supplies you are using and its specifications, we can't tell if the power supplies you picked are really adequate. You don't want to look at the Watts but instead you want to look at how much current can be supplied on each rail and compare that to how much current all of your devices need.

I recently upgraded my power supply in my server to a 660W Enermax power supply. Runs good. I have a couple Y connectors in it, but not many. It had 10 Hard drives, 1 DVD-RW drive, 1 DVD-ROM drive.

Having said that, if the estimate was that you needed 720W, and if your power supplies are typical power supplies that over estimate the wattage, then you probably need to upgrade your power supplies.

Joo

Share this post


Link to post
Share on other sites

Perhaps the psu's are powerful enough... on paper don't forget that psu's are advertised with greater capicity than they produce sometimes. And the psu's rails suffer when close to 100% power. if you have a Digital muti meter connect it between the yellow and black and also the red and black to test 5 and 12v rails.

Share this post


Link to post
Share on other sites

The 520W PSU is an Aspire (I can't remember the model number) and the other one is an AOpen one. The 300W was used for a couple of years to power an overclocked Thunderbird and around 5-6 hard drives (most of them scsi 10k rpm and old 7200rpm ones) and a burner, cd-drive and dvd-drive (all three scsi). The Aspire PSU has successfully powered an overclocked P4 2.53 and up to ~14 IDE/SATA disks for several months. I only added an extra PSU because I was afraid to let a single PSU run 20 drives (because of fire hazards or whatnot if it was overloaded). As I said earlier, I'm fairly sure that the two PSUs are enough for the drives.

What primarily convinces me that it's a cabling problem is that poking some of the wires will definitely make the disks click and spin up. That's the same thing that happens just before explorer crashes or the computer freezes - only then it does it by itself.

Unfortunately I don't own a multimeter, so I'm not able to check the PSUs.

While I'd prefer to trash all drives and go for fewer bigger drives, I'm afraid that making the cables myself are alot closer to what I can afford. I also really like the idea of ripping the connectors from old XT PSUs, but I don't know where I should get any. Either way I'll try the local electronic stores and see what they have.

Thanx for all the input, guys. I really appreciate it :-)

I'd still like to hear more about how you have done it, though.

Share this post


Link to post
Share on other sites

Digital muti meters cost very little so is well worth it. also you can get MOLEX connectors with noise suppresion, from

http://www.ocztechnology.com/products/powe...-hdd_power_lead

Again well worth it i also use the ocz powerstream PSU as this has varible rails

http://www.ocztechnology.com/products/powe...am_power_supply

the ability to change the voltage on the rails (live with a Digital muti meter got me near perfect 5v and 12v!! (i'm sure if you have a steady hand /helper you could do better)

Share this post


Link to post
Share on other sites

I have had this problem in the past.

I used a small flat-blade screwdriver to tighten up the collars on the female connectors - problem solved.

Just slide the blade between the plastic surround & the outside of the metal collar. Gently rotate the blade to adjust. If you over-do it, slide the blade into the slit in the collar, and widen it again.

One word of warning - if you make them too tight, you can make it very hard to separate the connectors. Many years ago a friend of mine pulled a pin out of the molex connector on his HD because of a tight connection. You have been warned, and I take no responsibility for any damage caused to cables, HD or PSU!!!

cheers, Martin

Share this post


Link to post
Share on other sites

I have had the exact same problem. When I would slightly brush against those Molex Y-Splitters, I could immediatly hear drives restarting. I agree that your Y -splitters are at least contributing factors in your premature drive failure. 'Cause once a drive starts resetting/recalibrating, its days are numbered. I was able to significantly reduce the inconsistant power issue from the Y-Splitters by not using them. They are all crap. A better alternative, is Directron's T Splitters They are only $2.00 each. They offer a 1:3 split, but more importantly, they are built entirely different. Instead of ganging up the wires at the actual molex plugs, which tend to cause the individual connectors to float in the socket, which I believe is at the heart of this problem. As shown here -- in a typical Y-Splitter:

3026.JPG

The T-Splitter on the other hand uses a continuous piece of wire, which runs perpendicular to all three molex connectors. Each contact in each Molex bites onto the wire with 4 teeth forming a square box. This box is locked into position by the molex, so there is no float or movement of the individual connectors. This guarantees power to all connectors.

The T-Splitter:

3028.JPG

3030.JPG

I hope this helps.

Jeffy82

Share this post


Link to post
Share on other sites

MartinP: Thanx for the suggestion. I tried it and it helped ALOT. There is still a drive or two that restarts once in a while, but I'll try some other y-cables when I find them. Before there were atleast 4 drives that restarted almost constantly.

Jeffy82: Although my problem is already much closer to a solution, I think I still have to get me some of them T-splitters. Sounds like the best solution. Thank you very much for the tip :-)

Share this post


Link to post
Share on other sites

I used to have this problem. Drives cutting-out was usually indicative that the PSU was about to completely fail. (Given a few more weeks, the PSU would be dead...) Go ahead and try what you like, but in my experience, I'd say the PSU's dying...

Or it may be overloaded. I ran a server with four burners and 18 HDs, and I used three PSUs: one 350W for the burners and two HDs, and two 300W PSUs powering eight HDs each.

Under that scenario, I never ever had any drive cut-out until a PSU was failing...

And those are quality PSUs. I average a failure about every six months. That's 24/7 with constant access...

Can't say I've ever had a PSU fail that was only powering the CPU. Coincidence, or are drives' power consumption that much different? (my guess is not a coincidence...)

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now