Thunderbolt 2 Versus SAS RAID solution

[aemilia scott]

I'm (finally) in the market for a larger and better RAID solution to replace my Caldigit card and drive.

I was wondering if I could ask for some expert advice about which way to move forward. I have a home-built Asus X99 Mobo and Chipset.

In terms of speed, what would my best option be?

- PC (Asus) ThunderboltEX II Card + Thunderbolt 2 Drive

- Atto RAID card + JBOD Enclosure

- Regular HBA + RAID Drive with onboard controller

Is thunderbolt 2 really matching SAS in terms of speed? Or is the bottleneck with drive type? Even brand recommendations would be lovely.

Thanks,
Aemilia

 

[Eric Bowen]

Thunderbolt2 Storage units with a good SAS controller inside can match SAS speed up to around 8 to 12 drives provided they are mechanical drives. Thunderbolt peaks out at 1.4GB/s or so. SAS at 12Gbs can push far higher than that and is what you definitely want when dealing with 16 drives or more or more than 4 to 5 SSD drives. If you are looking at 8 bay units then the deciding factor is the controller. If you get one of the Cineraid enclosures they use the Areca controllers. Those would be as good as the Areca SAS controllers for 8 drives as long as you running mechanical. That is what I would suggest. Overall though SAS has far more performance and bandwidth capability which means greater future proofing and upgrade options. Thunderbolt is portable. Those are deciding factors as well.

 

[aemilia scott]

Thank you very much. That's incredibly helpful.

Right now I have an ATTO h680 which I'm using with my LTO drive. Would you recommend I buy an ARECA 12Gbs RAID controller to replace my HBA, or should I buy an enclosure with hardware RAID in the enclosure and stick with the ATTO h680? Would you say putting the controller in the drive enclosure or in the HBA is a better move? Right now, I think my priority is more performance than portability. I'd look into a SAS to Thunderbolt box to transfer to my laptop if necessary.

Thanks again.

Aemilia

 

[Eric Bowen]

I would suggest the Areca 12Gbs over the Atto because the Areca comes with a fan and the caching/performance is better over all especially with the ram difference on the 1883 controller. Keep in mind the performance with 8 mechanical drives will be almost the same between a Cineraid Thunderbolt unit and 8 bay Sas unit. The performance might trend toward the SAS unit if the capacity used exceeds 60% of the volume in a raid 5 or 6.

 

[Jeff Kilgroe]

Well, if you have the H680 and not the R680, then you don't have a RAID controller right now, just a SAS host. So I would recommend upgrading to an actual RAID host so you can have RAID levels 5 or 6 via hardware. If you already have an R680 with RAID ability, then I would say that upgrading to the 12Gbps Areca (or ATTO) would not offer enough incentive to be worthwhile. The newer controllers have more cache and improved cacheing algorithms, but that isn't of huge benefit in R3D workflows or situations with large and different file access... You see much more benefit if you're running a database server or something with lots of smaller, but potentially more repetitive, data. 8 x HDDs isn't going to overload bandwidth on any of these controllers. With a 6Gbps and faster host, you'll need to run SSDs or use port multipliers with more HDDs in order to saturate the 6 or 12 Gbps on each channel.

Going with the Areca or Promise Thunderbolt RAIDs makes for a very convenient solution. They are robust and perform well and are very user-friendly. When you're talking about 8 HDDs, performance is going to be about the same between all these solutions as the HDDs will be the bottleneck 99% of the time.

 

[Bill Sepaniak]

If you decide to go with an ATTO R680, make sure that: (1) your case has plenty of fans / cooling. I have experienced thermal shut-downs with my R680 until I added extra case fans and a slot fan. (2) if you can, orient the R680 as far away as you can from your video card. The last thing you want is your video card venting hot air on the metal SAS connectors that plug in to the back of the R680. Those SAS connectors can actually get hot to the touch from the hot air venting from the video card, and that heat is then transferred to the raid card. Not good.

 

[aemilia scott]

Thank you as always, Jeff and Eric, for dropping excellent knowledge. and thanks for the tip, Bill.

I'm leaning toward SAS, because of the possibility of someday switching out the mechanical drives for SSDs. Additional prognostication question: do you expect the prices of SSDs to drop, or have we hit a plateau of sorts? My plan only works if SSDs become reasonable within the next two years. If not, then I suppose I'm better off with the Thunderbolt pathway.

Am I taking crazy pills, or are there no Asus ThunderboltII PCIe cards in the world right now? I'm not sure if I should be going off brand, but my board is the X99E WS, so I thought that would be a good bet.

 

[Jeff Kilgroe]

You have to use the ASUS TB2 card with your motherboard. They're very hard to find.

SSDs will continue to drop in price. We're going to see more focus on improving capacity and performance vs. driving the cost down on lower capacity units. Hard to say what will be out there in 2 years. We'll have 2TB SSDs instead whereas now 1TB is pretty much the biggest with a SAS interface. Price per GB will be less than it is now, but hard to say how much less.

 

[Eric Bowen]

The Asus Thunderbolt EX2 cards have been out of stock in NA for 3 weeks plus. The ETA was suppose to be yesterday or today but still not available yet. Likely the container is still going through customs. SSD pricing is rather sporadic because density walls often hold pricing in the current range until that wall is breached. Then you see large pricing changes. The current density wall may last 1 year or then again maybe less. Its hard to say. I wouldnt expect major drops in pricing for the 1TB drives until they reach the next density as Jeff suggests. The cost of MLC doesnt fluctuate much when production is peaked.

 

[aemilia scott]

Top notch. Okay.

What JBOD enclosures do you guys use or recommend? I'm leaning toward the Areca ARC-1883ix or X 12gb controller.