So I was looking at getting this chassis:

 

http://www.ebay.com/itm/4U-NAS-Supermicro-24-bays-Storage-Server-Chassis-SC846E1-R900B-846EL1-2x-PS-/141918972284?hash=item210b07a97c:g:7KAAAOSwv0tU47SJ

 

This whole sas expander thing confuses me though. The backplane says it is compatiable with SAS/SATA 3 Gb/s drives, and has a single 3 Gb/s interface. If I'm reading correctly, a single WD Red 3TB drive has a max throughput of about 1.5 Gb/s.

 

So if I'm interpreting all this correctly, all 24 drives would be pushed through a single 3 Gb/s pipe and be bottlenecked if I'm reading from more than 2 drives at once?

 

I'm wanting to build an easily expandable plex media server for about 3-4 users max, which 3 Gb/s might be fine for that, but what would you guys say?

 

Thanks.

I have the BPN-SAS-846EL2 SAS expander and find that it works well.  The backplane has a sas connector on it so if your motherboard has sata ports on it, you need a reverse breakout cable to connect the backplane to 4 sata ports on the motherboard.  The backplane connects the 4 sata ports to 24 drives. As long as you are not accessing more than 4 drives connected to the backplane at the same time, there is no performance hit. For this reason, I don't put my parity drive on the backplane.

 

There is a bracket you can buy that attaches a 3.5 HD to the side of the power supply.  See this link:  http://www.ebay.com/itm/191819144865?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

The 846 case can take two of them.  If your MB has 6 sata ports, connect 4 to the backplane and use the other two to connect parity drives mounted to the side of the power supply. 

 

About the only time the backplane becomes a bottleneck is during parity checks. This is because all the drives are being accessed at the same time. Still, it works amazingly well.

do you know if this backplane will support larger than 2Tb drives? the seller says it will not support just wanting to verify.

do you know if this backplane will support larger than 2Tb drives? the seller says it will not support just wanting to verify.

 

It will not, some people have reported that it may see 4 drives larger than 2TB, but will not recognise any additional devices beyond those 4 (even if they are 2TB or less). It most likely will not see any of them.

Expander has to be connected to a SAS HBA, it won't work on on board SATA.

 

As for bandwidth, with a single SAS link you'll have 1100MB/s for all disks during a parity check/disk rebuild, so it will be on the slow side with many disks.

I have a TQ backplane for this case.  It's a direct pass through backplane and is only limited but the controller you use. Works well. Currently have 12 3tb drives and a bunch of SSD's.

 

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I have some of the SAS1 backplanes and can put 23 disks larger than 2TB in it and it runs just fine. Now can I guarantee it will recognize every drive from every manufacturer >2TB? Nope, I can't. But I can with 100% certainty tell you that most (NOT all) who say they won't recognize drives >2TB either currently don't or never have owned that chassis with a SAS1 backplane. They simply regurgitate false information they read somewhere else.

 

It's not officially supported from Supermicro but not a single one of my 846 chassis with the SAS1 backplanes have an issue seeing drives >2TB as long as the server isn't fully populated meaning 23 or less drives out of the 24 slots. I'm not saying I recommend doing this, just saying it is entirely possible.

 

Now as to the speeds of SAS1 VS SAS2/3. That all depends on your use case. If you going for some massive virtualization lab running 24 SSD's, you might have a speed issue. If your running something like a media server, you won't even come close to saturating a SAS1 link anyway. Especially if your only running a gigabit network.

 

Hope that helps

 

**Edit. Echo what johnnie.black said. You will see a bottleneck during parity builds/checks if your filling the server completely up with drives on the SAS1 backplane.

 

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