PSU and lots of HDs

[VirtualLarry]

Trying to decide what to do for my fileserver. I was originally going to use a 550W SuperFlower (that seems to have a lot of emphasis on the 5V line, rather than the 12V line). But after seeing someone else's calculation for PSU needed for HDs, I decided it would be safer to go with the 750TX PSU. One reason for using the SuperFlower is that it has 10 molex connectors. I want 16 HDs in the tower (three RAID-5 arrays of five drives each, plus the boot drive). I'm using a ThermalTake Armor case and some Lian-Li EX-23 bays to fit 15 HDs in the front, and then the Armor has several HD bays next to the PSU.
Well, IIRC, the 750TX has 8 molex and 8 SATA connectors. I have plenty of molex-to-dual-SATA power adaptors that I was planning on using. So I should have the connectors covered.

The question is, which motherboard should I use, and how will that affect the PSU. I'm trying to obtain a GA-P35-S3G, which is a P35 mobo with five PCI slots. That's a modern mobo that draws off of the 12V line, so that won't be a problem. But if that doesn't work out, I might just use my old Athlon XP rig, with a KT4V-L mobo. IIRC, that mobo draws most of it's current off of the 5V line. I'm worried that if the 750TX has most of it's current on the 12V line, how much of the 5V line do the HDs take, and is there enough room on the 5V line to run an Athlon XP mobo besides.

Do HDs take most of their startup current on the 12V line (for the motors), or do they take a lot on the 5V line when they start up too?

So far, I have five 500GB Seagate 7200.11 drives, and five 750GB Seagate 7200.11 drives. According to Seagate's desktop HD reference, both drives are rated at 3.0A on the 12V line during spinup.

7200.11 750GB
5V 0.65A
12V 0.6A

7200.11 500GB
5V 0.65A
12V 0.42A

Those appear to be idle ratings, because the load ratings in the Seagate desktop HD reference are higher. Unfortunately, they only give total wattage, and don't break it down by rail. They list 11.16W for the 750GB, and 11.6W for the 500GB.

My SuperFlower 550W PSU, has this for ratings:
3.3V - 28A
5V - 55A
12V - 22A
Combined 3.3V + 5V = 275W
Combined 12V = 264W
Combined 3.3V + 5V + 12V = 530W

So with only 22A on the 12V, that wouldn't be enough for my 10 HDs to spin up (3.0A x 10 = 30A), nevermind if I added five more HDs.

So 750TX it is:
+3.3V@30A
+5V@28A
+12V@60A

Looks like the 12V line has more than enough amps for 16 HDs. 16 x 3.0A = 48A. (There isn't going to be a powerful GPU in this rig, it's a server.)

The question is, is the 5V line powerful enough to run the 16HDs AND an Athlon XP mobo?
If you figure the CPU and chipset take 80W total, then that's 16A on the 5V line. 28A - 16A = 12A left for the drives, divided between 16 drives, that's only 0.75A per drive. Pretty close to Seagate's specs. Too close, IMHO, considering that the PCI cards might draw off of the 5V line too.

 

[mpilchfamily]

HDD rely on the 12V for everything. A singel cable from the PSU should not have more then 12A running threw it. So don't put more then 4 drives on a single cable. But most cables only have 3 molex connectors per cable.

 

[dangman4ever]

The 750TX is more than enough for 16 drives and an Athlon XP Mobo. I know of one person using that PSU to power the following specs:

Biostar TF720 AM2+ Motherboard w/ Onboard Video
AMD Athlon X2 4050e 45w Processor
2 x A-Data 2GB DDRII 800 Memory Kit
2 x Supermicro SAT2 MV8 SATA Controllers PCI-X 8 Port
Norco 2040 20 Bay Hot Swap Rackmount Case w/ 1 Internal HDD Bay
Corsair 750TX 750W Power Supply
1TB Seagate SATA Drive for Operating System
20 x Seagate SATA Drive for Storage
Microsoft Windows Home Server Operating System

That's 21 hard drives! You can see that setup here (go back a page in the link below to see a similar setup but with a PC P&C Silencer 750):
http://networkisdown.com/showthread.php?t=276&page=10

 

[Evadman]

Not your exact question, but I had good luck with a Norco 20 bay hot swap case that will end up cheaper than the solution you have chosen or are about to choose.

My review:
Pros: There is quite a bit of room in this case in almost all areas (see cons). The case is also covered on the top and bottom with contact plastic to protect from scratches during shipping, just in case that is important to you. The hot swap drive trays are a tight fit, and take some manuvering to get in, but they do not feel loose at all like another reviewer mentioned. I tried to pull one out while powered on and latched, and there was very minimal movement. Connection to the drive was not lost either.

The build quality on the trays is not what I would call exceptional, but it gets the job done. The holes line up on all trays, there were no manufacturing defects that I could find. (I have seen some trays on other servers with holes that do not line up well)

The 5 fans behind the drive bays move lots of air quitely (for a server), but can hit cables if you are not careful. I suggest buying 5 fan grills for thos fans to keep cables (and fingers) away from the fans.

Cons: The distance between the back of the hot swap bays to the front of the fans is pretty short at about 2.5 inches. Since there are actually 20 SATA connectors and 10 power connectors on the backplane, the cabling between the backplane and fans gets very tight when full.

The pictures show SATA and SAS connectors on the backplane, but there are only SATA connectors. I was disappointed to find that the backplane doesn't actually have SAS connectors. If all you need is SATA, I would not hesitate at buying this case.

Finally, the accessory box that holds the screws, backplates and such was not securely fastened in the box; it looks like it was just tossed in. The box opened somewhere in transit, and the screws were all over. I had to literally disassemble the case to get all the screws out from between the components and dividers in the case.

Because of the missing SAS, screws and LED's this only gets 3 stars/eggs instead of 5. For the price though, this is well worth it.

Other Thoughts: The backplane is actually made of 5 separate backplanes running horizontally across the 4 horizontal drive bays in each row. Each backplane has 4 SATA connectors and 2 power connectors (regular molex connectors, not SATA power connectors). This gives you more options in purchasing a power supply.

As another user mentioned, the green power LED's have a lot in common with the sun. They are bright enough to see from several miles away. However, the activity LED's are more of a suggestion. You really do need to get within a few inches of the drive bay to see the activity light blink, even in a dark room. Forget about trying to see it if the lights are on in your server room. This makes identifying failed drives (by blinking activity lights) very difficult.

The drive LED's are actually on the backplane, and light pipes are used to carry the light to the front of the drive bay so it can be seen. This may lead to the horrible visibility of the activity LED's.

 

[VirtualLarry]

Oh great, NOW you guys tell me about this nifty 20-bay hotswap rack-mount case.

Does it require a micro-ATX mobo, or can it take a standard ATX?

 

[Modelworks]

I would set up lots of drives using staggered spin up or power up in standby.
That allows each drive to spin up one at a time in whatever order is set up.

Anyone know which motherboards offer the feature in the consumer market ?
I know there are cards and server boards with it, but I don't think it is too common for consumer boards.

 

[Evadman]

Originally posted by: VirtualLarry
Oh great, NOW you guys tell me about this nifty 20-bay hotswap rack-mount case.

Does it require a micro-ATX mobo, or can it take a standard ATX?

it can take up to an extended ATX I think. the motherboard area is huge. I have a regular ATX in there and there is a ton more room.

Originally posted by: Modelworks
I would set up lots of drives using staggered spin up or power up in standby.
That allows each drive to spin up one at a time in whatever order is set up.

Anyone know which motherboards offer the feature in the consumer market ?
I know there are cards and server boards with it, but I don't think it is too common for consumer boards.

You can get a pretty cheap raid card that supports staggered spinup

 

[VirtualLarry]

The problem is less of the RAID cards supporting staggered spinup, and more of a drive problem. WD SATA HDs have a jumper to set for staggered spinup, but Seagate drives have some sort of wacky mechanism, by which the drive does staggered spinup, if a certain pin in the power connector is grounded or not. Since I'm using molex-to-SATA splitters, mixed with the native SATA power connectors off of the PSU, then that doesn't seem to be an option.