RAID Block Size for 4K/5K .r3d work?

[5050]

Hi guys,

Setup: Sonnet Tempo SSD Pro PCIe + 2 x Samsung SSD 840 Pro 512 GB

Question: What's the best Raid Block Size setup (16K, 32K, 64K, 128K, 256K) for a striped RAID 0 setup using the components above? Will be using Mac OS X Disk Utility to format this setup for 4K and 5K .r3d work in Premiere and DaVinci Resolve.

Thanks!

Jonathan

 

[VirtualRain]

I did some testing on my SSD RAID0 array (3x Vertex4 SSDs) when I implemented it. Basically, the old school thinking of picking a stripe size based on the type of data is no longer relevant with SSDs. The actual design of the SSD plays more of a role (eg. NAND page and block size). So the only way to determine what's truly best is to run a variety of tests on your setup with different stripe sizes before you commit. Get a copy of QuickBench so you can actually do some Random I/O testing as well as sequential. Having said all that, the differences are not likely to be that large, so if you don't have time to invest in it, just pick 32K and run with it.

Here's an excerpt of my findings...

Optimal stripe size:

I've always subscribed to the school of thought that stripe size should be a function of the type of data you're storing/accessing... a small stripe size for smaller files... and larger stripe sizes for larger files. When SSDs came along, the write amplification penalty due to large NAND page and block sizes also supported the use of larger stripe sizes. So when I started into this project, I was fully expecting to run as large a stripe size as I could.

In my research however, I found another guy that had been testing various RAID0 stripe sizes with the Vertex 4 (on a PC) and found that they performed better with smaller strip sizes... right down to 4KB. I decided to do a bunch of stripe size testing of my own before committing to one on my array.

Using the x16 slot for my testing, I tried 128K, 64K, 32K and 16K (the smallest OS X RAID0 allows) and the results were consistently better with decreasing stripe size. I forgot to take a screen shot of the benchmark tool on the larger stripes, but if I recall correctly, the differences were significant between 128K and 16K for larger sequential transfers (on the order of around 100MB/s but still less than 10%) and insignificant at lower 4k transfer sizes.

Here's the full thread... https://forums.macrumors.com/threads/1504491/