Supermicro Backplane: SAS2-846EL2/847EL2

[DreadStarX]

Hey Guys and Gals,

I work in a DataCenter, and recently we've removed about 10 - 20 Supermicro 36/24/12/8/4 bay servers. I ripped apart one of the 36 bays to find out what kind of Backplane it has. It has a BPN-SAS2-846EL2/847EL2. Now, my question is; are these worth my time? Can I stick 6TB Drives in it? 8TB? 10TB? 12TB?

I've got a project, and if I can succeed in doing it, I'll have 100+ 6TB drives in 2 Full Size Towers. If I'm successful in that endeavor and cooling isn't a problem, I'm going to buy a 900D, and mod it for a storage tower.

 

[SweetAndLow]

Hey Guys and Gals,

I work in a DataCenter, and recently we've removed about 10 - 20 Supermicro 36/24/12/8/4 bay servers. I ripped apart one of the 36 bays to find out what kind of Backplane it has. It has a BPN-SAS2-846EL2/847EL2. Now, my question is; are these worth my time? Can I stick 6TB Drives in it? 8TB? 10TB? 12TB?

I've got a project, and if I can succeed in doing it, I'll have 100+ 6TB drives in 2 Full Size Towers. If I'm successful in that endeavor and cooling isn't a problem, I'm going to buy a 900D, and mod it for a storage tower.

Pretty sure those are the backplane that work the best for most people. Wait for a couple more responses to be sure.

Sent from my Nexus 5X using Tapatalk

 

[scrappy]

I have essentially the same version in the 12 bay form. It has never exhibited any problems that would be cause for concern regarding FreeNAS/ZFS use.

 

[DreadStarX]

I have essentially the same version in the 12 bay form. It has never exhibited any problems that would be cause for concern regarding FreeNAS/ZFS use.

Awesome. This is what I wanted to know. If I'm successful, I should be able to fit 3 - 4x 846EL2 BPs in a single tower, and have the cooling capacity to do it. I haven't been this excited since I got my first IT job. My coworkers have all said that it isn't possible to run 3 - 4 backplanes from a single tower. Maybe, mabe not. Power is the biggest problem :) I'll create a new thread when I start on it.

 

[tvsjr]

I'm running those exact backplanes with that same 36-bay chassis. Works good, lasts long time, all that.

3-4 backplanes? One box? 96 drives? Power is easy... 96 drives is ~576 watts. There are plenty of power supplies that'll drive that. Heat is your big problem. Ever notice how most SANs tend to use multiple drive shelves? There's a reason - power and heat. In fact, even the 36-bay Supermicro chassis suffers from slightly warmer temperatures for the 12 drives on the rear.

 

[DreadStarX]

I'm running those exact backplanes with that same 36-bay chassis. Works good, lasts long time, all that.

3-4 backplanes? One box? 96 drives? Power is easy... 96 drives is ~576 watts. There are plenty of power supplies that'll drive that. Heat is your big problem. Ever notice how most SANs tend to use multiple drive shelves? There's a reason - power and heat. In fact, even the 36-bay Supermicro chassis suffers from slightly warmer temperatures for the 12 drives on the rear.

Yeah. I started thinking about the heat. I've been watching the temps on my 10 bay box now. I plan on using a H440 case, it supports 3 fans in the front, 3 on top, 3 on the bottom. My house is AC'd at 60 Degrees. I bitcoin mine and all my cards are rockin' 75 degrees or so.

I'm looking at 2 24 bay backplanes. That'll give me sufficient spacing between them to help tunnel the heat out. As for the power, sure but to power two or more BPs, I need 6 4-Pin Molex connectors per backplane. I was going to look into custom making the cables for it, otherwise I'd have too many cables running to it.

Supermicro has 45 Bay, 60 bay, and 90 bay jbod boxes. The heats gotta be astronomical on those. I think 2 of them are plausible, 3 to 4 would be plausible in a Super Tower, just need a way to deal with that many drives. Once the case arrives and I've gutted it, i'll start working on it. Posting pictures over time.

 

[Ericloewe]

96 drives is ~576 watts.

Not even close. Think 3kW.

 

[danb35]

...and to directly answer the other question, those backplanes are what I have in my server, and they (well, the front, 4U one; I haven't needed to use the rear bays yet) work fine with 6 TB disks. Haven't tried anything larger yet.

 

[DreadStarX]

Not even close. Think 3kW.

Yeah, I agree with this portion. 600w wasn't even close to what I was thinking. I figured I'd need at least a 2,000 Watt PSU to handle all of the modular plugs for it.

...and to directly answer the other question, those backplanes are what I have in my server, and they (well, the front, 4U one; I haven't needed to use the rear bays yet) work fine with 6 TB disks. Haven't tried anything larger yet.

Awesome, I have 6TB HGST HDDs. Less than 3k usage hours, roughly 3 months worth of run time. They've been sitting idle for 3+ years.

My next question is, can I daisy chain all of my backplanes together, or at least 2 of them?

 

[danb35]

My next question is, can I daisy chain all of my backplanes together, or at least 2 of them?

I believe you can chain them, but I haven't tried myself.

 

[tvsjr]

Not even close. Think 3kW.

Sorry, but I disagree.

WD Red:
https://www.wdc.com/content/dam/wdc/website/downloadable_assets/eng/spec_data_sheet/2879-800002.pdf
For the 8TB model, 6.4W average during read/write activity. Max consumption is 1.79A (spin-up), or 21.48W.

For fun, let's look at some HGST 15K drives:
https://www.hgst.com/sites/default/files/resources/USC15K600_ds.pdf
The 600GB is 7.8 watts operating. Max consumption isn't listed.

So, assuming you don't do something foolish like try to spin up all of the drives simultaneously (and most any server-class system is going to support staggered spinup), you'll never see anywhere close to 3KW. With 96 Reds, you'd see 2.06KW in the worst case - no staggered spinup, etc. - for a handful of seconds, falling back to 614W in the worst case (all drives 100% utlilized/active). And the primary concern I was addressing was handling the heat... where the initial inrush isn't a major factor in the overall steady-state thermal management of the system.

 

[Ericloewe]

For the 8TB model, 6.4W average during read/write activity. Max consumption is 1.79A (spin-up), or 21.48W.

Measurements exist that cast doubt on the validity of the datasheet's claims - check the PSU sizing thread.

So, assuming you don't do something foolish like try to spin up all of the drives simultaneously

Relying on staggered spinup implies relying on the HBA to handle things intelligently and to not lose its configuration and relying on the admin to not forget that important little detail if the controller is replaced. None of those three types of trust are well-placed.

you'll never see anywhere close to 3KW. With 96 Reds, you'd see 2.06KW in the worst case -

With actual measured power draws, that figure is much closer to 3kW. And it doesn't include anything else in the system. The fans alone can easily add hundreds of watts to that figure, when cramming so many drives into one chassis - and they're notoriously nasty when it comes to startup current.

And the primary concern I was addressing was handling the heat... where the initial inrush isn't a major factor in the overall steady-state thermal management of the system.

Sure, thermal management can be done with the steady-state power figure, but that is not the worst-case for PSU sizing.

 

[danb35]

Measurements exist that cast doubt on the validity of the datasheet's claims

...and other measurements (to wit, mine) cast doubt on the validity of those measurements. But still, better to have the headroom, I'd think.

 

[Ericloewe]

But still, better to have the headroom, I'd think.

My thoughts precisely. Until we have a third set of measurements, it's best to be cautious.