RAID Recommendations

Building a new workstation to replace my 6 year old Mac Pro for DaVinci Resolve and Motion Graphics. Any thoughts or opinions on a 6 drive RAID 5 vs an 8 drive RAID 5 of the same storage size (either 8 or 12TBs). Are the 8 drives that much faster and worth the risk of the extra disks in regards to bad sectors and read/write errors? Also considering RAID 6 if it isn't a huge performance hit.

Any help or thoughts would be greatly appreciated. I would really like to build a smaller system in a smaller case by going with 6 drives...but I don't want to create future expansion issues by limiting my drive space and case size.

I will be using a Areca ARC-1882IX-12 6Gb/s SAS/SATA RAID Adapter with 4GB of cache in a PCIe 3.0 full 16X slot. The same setup that ProMax uses for their ProMax One. They get around 1200MBs off of 6 drives in RAID 5.

That's what I thought as well when I heard and saw the benchmark at NAB this year. Part of me wonders if they had the cacheing enabled on their AJA benchmark tool. I plan to copy their setup exactly but probably with 8 drives. So we shall see.

Yeah those numbers seem realistic to me. I'm getting 560MBs tops off my 8 drive external SAS connected to an old ATTO R380 in a 4x slot instead of 8x.

Most of my color grading deliverables lately have been at 4K recently. Plus when I'm doing my Motion Graphics work your talking about sometime over 100 layers in AE with 5-8 of those being 1080P to 3K video sequences. So the faster the better.

I just would really like to have a smaller system footprint with the 6 drives instead of the behemoth tower that will be required with the larger array. But I don't want to be stuck with only 6 drives and no upgrade room and regret it I suppose.

I would suggest not to go with Raid 5, but Raid 6, or to have a very good read at http://www.miracleas.com/BAARF/.

I have had Areca controllers for years and woul'nt recommend them. Tech support has been very unresponsive. I have to work with lots of options disabled (including Tagged Command Queuing, including Read Ahead), because otherwise the Areca reliably make the computer crash when the array is > 60% full (2x12 sata-disks in SAS expanders). So I get degraded performance. It's a Macintosh driver problem. "Realibly crashes" : consistent accross Areca Cards (1680 and 1880), computers (different mac pros), hard drives (consumer and enterprise-grade, operating systems (Leopard and Snow Leopard), card firmware and drivers. If I had to start from scratch I would go with Atto. For the moment I don't, because I prefer the devil I know, I need those Raid volumes, performance though degraded is still fine for 2K DPX read/write at the same time (> simultaneous 300 MB/s read & write) and the stability of the Raid Volumes (one Raid 6 on one computer, one Raid 60 on an other) has been perfect.

It makes no sense to test a RAID array with something like Aja System Test. The Write test are not accurate because the Raid cache speeds up enormously the thing (I have 3 GB RAM on my Raid Card, those are filled almost instantly, 16 GB is not enough). Then the Read test are not accurate either, because the write cache is still getting emptied. I would suggest going with http://diglloydtools.com/disktester.html ... or duplicating a dpx full of DPX, or R3D (whatever you work with), and check out Activity Monitor to see what is the real-life read/write speed.

Michael Cinquin


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