Is it worth the approx $1000 to replace the spinning disc 2 x 2TB HDs in the raid with SSDs? Would replacing the raid with a single SSD be worth it? Is there a significant boost?
A lot of the time-watching is in rendering and output but there's also the frustration of having lots of folders and sequences open in Premiere with heaps of filters on clips and the inevitable Premiere crash. Would SSDs improve that situation?
Not knowing much about Premiere, I'm assuming that most of the waiting is either waiting for the RAID array to parse through the folders/load the files, or running out of RAM and paging to the scratch disk (or both).
If it's the latter (running out of RAM), then I would suggest waiting for the new RAM and seeing if that helps by itself. If it's the former (waiting on the RAID stripe to load files), then it's a bit more complicated:
- If a typical workflow has lots of smaller files spliced together and streaming directly off disk, then even a single SSD may be faster, as SSDs excel at small files and concurrent accesses. An example of this might be a multi-angle shot with several soundtracks and filters running at the same time.
- If your typical workflow is a handful of larger files (several hundred megabytes per clip, for example), the benefit may be smaller. RAID-0 stripes with hard disks tend to be very good at high-MB/sec streaming. An example of this would be a few longer cuts with very few edits/added effects.
For either case, you should also consider the possibility of running into the limitations of the Mac Pro's built-in SATAII - the maximum throughput even from a dual 2TB-SSD stripe will be around 550 MB/sec. My dual 4-TB stripe (two 7200rpm hard disks) can manage ~300 MB/sec with a large enough file. That means you may need to budget for a PCIe card with additional SATA3 or even NVMe connections to see a significant benefit (and there's a few threads discussing the pros/cons of that if you thumb through the first 2-3 pages of this forum).
So all told, I would just watch Activity Monitor while you're editing/rendering a file. If "Memory Used" (in the Memory tab) exceeds 24gb while you're working, you'll get the most benefit from the RAM upgrade. If "data read/sec" or "data written/sec" (in the Disk tab) is less than, say, 30-60 mB/sec while you're editing a file, then you might benefit from just a single SSD. If "data read/sec" or "data written/sec" exceeds 200-300 mB/sec while working, you
could benefit from a SSD stripe but you should also look at NVMe or an SATA3 card as options.
[edit]
Assuming the CPU/GPU upgrade (and the pending RAM upgrade) are already sunk costs, you may also consider that every significant expenditure from here on out could go towards a new workstation instead. Assuming you're locked into a CUDA workflow, you should keep an eye on whether NVIDIA eGPUs become officially supported in MacOS - in which case an iMac Pro with a Pascal/Volta/whatever eGPU will almost certainly be faster than whatever you could upgrade the 5,1 into. If Premiere ever gets Metal support added you won't even need eGPU (but this seems much less likely). At any rate Apple will probably stop supporting the 4,1/5,1 after MacOS Mojave, so your computer's running on borrowed time anyway unless you stop upgrading the OS.
