Help spec my SC846 build! (fileserver + light virtualization)

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NickM

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Jul 19, 2015
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I currently have ~12 3.5” mechanical drives crammed into a desktop tower server for my unRAID setup, and am looking to expand. I’ve built a dozen or so home PCs/consumer-grade servers, but this will be my first time working with enterprise-class hardware. I tried to do my research ahead of time to come at this intelligently, but feel free to direct me wherever I need to go.

I’m currently running this setup on a Phenom II X2 with 4GB ram. It’s borderline-adequate, if a bit slow, so I don’t “need” a huge speed upgrade, but it would always be nice if it can be done cheap.

Needs/wants for an upgrade:
  • Lots of 3.5” mechanical drives
  • Virtualization with passthrough support
  • Don’t need a ton of horsepower, just expect to be doing some light home media/file server and virtualization usage. Dual socket is probably overkill, but not a problem if it’s cheap.
  • Reasonable power consumption -- if spending an extra $100-200 now will recoup the difference in electric costs in a year or two (assuming mostly idle), it’s probably worth it
  • Low noise levels (server will likely be in the same 12’ x 10’ room as my ‘home office’) -- WifeApprovalFactor is important.
  • Don’t need super-insane uptime / redundant everything. This is just for personal use.
  • ECC ram -- bad experience with bitrot
  • Fairly low cost. Let’s say below $500-600ish all-in?

After some eBay searching and some reading here, I came across this listing from CertifiedServers for a Supermicro SC846E1-R900B with X8DTE-F motherboard and BPN-SAS2-846EL1 backplane, which seems like a good ‘starting point’ to ask them to customize something.

I don’t have a particular motherboard/cpu in mind, so I figured I’d buy what it comes with and grab a pair of Xeon L5630’s or X56something’s ($50-$150, depending). Plus a 6x4gb ECC DRR3 pull for $100ish, unless someone has a better idea for inexpensive-but-decent cpu/motherboard

I already have a crossflashed m1015 card -- I believe this will provide the correct interface to the backplane via a single mini-SAS cable? And with the SAS2 expander backplane and mechanical drives, I believe there should be little-to-no bottleneck (simultaneous 100+MB/sec on 20-24 drives)? Please correct me if not!

PSU thoughts:
  • See if they’ll put in a single PWS-920P-1R, or buy the server with no PSU and get one of those or a -SQ on my own
  • Or, just buy consumer PSU that’s actually quiet and stick it to the side of the case like this guy

Additional questions:
  • What heatsink/fan would you recommend for the CPUs in this build? I saw a reference somewhere to needing a Supermicro-specific heatsink for the mounting screws
  • Will the BPN-SAS2-846EL1 expander allow individual drives to be spun down/idled when not in use?
  • Are there better values available for motherboard/CPU pulls such that I should just get the bare chassis and order everything else separate?

Am I missing anything??


Thanks!
 
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neo

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Mar 18, 2015
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I forgot the threads, but there was at least 3 similar ones posted recently. Have you given it a look?
 

NickM

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I've read all the threads on the chassis that I could find, and was largely looking for input on
a) compatibility with my existing hardware
b) power supply
c) if there are good motherboard/cpu options that I'm missing
 

T_Minus

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a. Your HDs will work fine with the 846 backplane.

2. The non 80+ are very loud, the 80+ is loud, the platinum are quiet, the sq are, well, super quiet :) Prices go up A LOT as you work your way up. I'd try an 80+ Gold first (20-35$ each only, and they should put one in for you instead of 2 of others for 0 price difference)

3. There are, but not for your budget. I'd stick with he L5630/40 and the 2p 1366 until you can afford something more powerful if warranted to put in there.

Unless you have a lot of time 1366 will be cheapest, E5 v1/v2 aren't much more if you can really look, and spend time researching deals. BUT, it will be more $ no matter what since the 2P boards aren't $100-125$ like the 1366 ones (or incldued as you found) and the 2P capable E5 are even more $ for basic CPU.

A E5-1620 V2 for $150 and a 1P E5 board for $150-200 would be a powerful system that's a bit more updated but leaves 0 room to expand other than higher-end single CPU... you could always start with 1P in a 2P E5 board if you want room for expansion.
 
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NickM

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Welllll darn. I got in touch with them, and turns out they're actually out of stock of the SAS2 backplane, and have pulled all the SAS2 ebay listings.

They've got the SAS1 expander backplanes still. I'm a little unclear on where the bottleneck of SAS1 vs SAS2 comes in on these backplanes -- does it slow the drive<->expander link, or the expander<->HBA link? It seems like the former wouldn't really make a difference for mechanical drives, but the latter would be a huge problem.

In other words, what's going to be my total max aggregate drive bandwidth with the SAS1 backplane? Can I still get something near 80-100MB/sec on 20-24 simultaneous drives? Is it still worth pursuing with this setup?
 

T_Minus

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EXPANDER<->HBA = POSSIBLE SLOW DOWN.

3GB/s is the link between the drive and backplane on SAS1.
6GB/s is the link between the drive and the backplane on SAS2.

The aggregate bandwidth is different, and that's what I think you're asking if you can still get 2.4GB/s on SAS1. Is that correct, my understanding of your question?
 
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NickM

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The aggregate bandwidth is different, and that's what I think you're asking if you can still get 2.4GB/s on SAS1. Is that correct, my understanding of your question?
I think that's what I'm asking, yes :)

The calculation I've seen referenced in the past for the SAS2 backplane goes something like:
6Gbps * 4 channels = 24 Gbps = 3 GB/sec theoretical -> 2.4GB/sec real-world
2.4 GB/sec / 24 drives = 100 MB/sec per drive​

What do those numbers look like for the SAS1 version?
 
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T_Minus

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So you figure that you have 4x3Gbs or 4x6Gb/s.

I don't think you could run into 1.5GB/s or 3GB/s with your setup.
 

T_Minus

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Did you have a plan for your file system? Cache drives? OR anything else like that it would help determine more.
 

NickM

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The majority of the file system will be unRaid for bulk storage. Probably a few assorted drives passed through directly for VMs.

I definitely won't be approaching even 1.5GB/sec aggregate bandwidth in a typical day-to-day use case, but on the other hand I don't want an array rebuild to take an eternity either. My current hardware ranges from a simultaneous ~80-110MB/sec per drive over the entirety of an array read consistency check, and I'd like to avoid dramatically reducing performance in the process of "upgrading"

Are you asking about a "cache drive" in the unRaid usage of the term, or in a more traditional sense? I don't really like the "unraid cache drive" methodology for most data.
 

katit

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I currently have ~12 3.5” mechanical drives crammed into a desktop tower server f
Nick,

Those 12 drives, what size are they (Capacity) ?

If you have drives < 1-2TB each it may be $$ savings in replacing them with large drives, did you think about this?
 

NickM

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Those 12 drives, what size are they (Capacity) ?

If you have drives < 1-2TB each it may be $$ savings in replacing them with large drives, did you think about this?
They're a mix of sizes (beauty of unRaid). Something like (4) 1.5tb; (4) 2tb; (4) 3tb. I just buy additional drives as I need them at whatever price point is best at the time

How would replacing the smaller drives with bigger ones save money? Or do you just mean avoiding the need to go through this whole upgrade process? Where's the fun in that?? ;)
 

katit

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I was thinking in terms on energy efficiency. Roughly 1W - $1/year (at least in our area). If you have 5 drives at 10w each - it's $50 per year. If you replace with 1 drive - it's $40 per year savings..

If your drives spun down - thats another story. It depends on your setup.

And no, there is no fun in not upgrading - I'm going through this myself now. 486 chassis for 6 drives :)
 

neo

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If you have 5 drives at 10w each - it's $50 per year. If you replace with 1 drive - it's $40 per year savings..
You still have to calculate in the additional cost of the larger drive. In many cases, there is still a cost prohibitive factor. The small incremental savings on energy do not outweigh the (much) more expensive drive.
 
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katit

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Going price on 2Tb drive - $50. Sell 2 of them - $100, Get 4Tb drive for $150. In this case ROI - 4-5 years but no need to build system to support too many drives. Math can go many ways of course. I'm just thinking that 500Gb drives need to be ditched if there is many of them..
 
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rubylaser

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UnRAID spins down your drives when they aren't in use, so they likely aren't drawing anywhere close to 10 watts on average because most of the time they would be in standby. I would consider replacing the 1.5TB drives because you can easily achieve more density with a couple 3 or 4TB hard drives (also, those drives are pretty old at this point).
 
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NickM

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I snagged a SAS2 SC846 with X8DTE-F and a 1200W gold PSU! Since the motherboard was practically thrown in for free and the CPUs are cheap, I'll plan that this setup will hold me over until I can upgrade to lower power cpu.

Time to round out the build now...

4GB RDIMMs on ebay seem to be the sweet spot in GB/$, and I don't foresee filling this system with more than 12x4=48GB. I see a few listings for 4GB DDR3L at similar price as DDR3 ($10/stick vs $12/stick) - is it worth going with the low power option?

Looks like a single L5640 is about the same price as two L5630's - my inclination is to go with the single L5640 for now with 4-6 x 4GB rdimm's, which leaves upgrade options open for later

Look good? Any thoughts?