...What is a good external drive system to pair with the iMac Pro? I'm a photographer with a little bit of video, and I have over 5TB of data right now...Currently with my Mac Pro I use the Pegasus2 (Promise Technology) 8TB with 4 bays in a RAID 5 to give an effective capacity of 6TB....For the iMac Pro I was thinking of abandoning RAID and going with either LaCie Thunderbolt 3 10TB or a similar G-Technology rig. Redundancy to be gotten by buying two of these...
I have the same Pegasus2 plus several other arrays; the LaCie isn't nearly as fast -- it's a single drive. However it's nice looking and supposedly quiet.
I have several OWC Thunderbay 4 arrays I use in RAID-0 and I have an off-line redundant spare for each one. Instead of hardware RAID I use SoftRAID, although that's not strictly necessary for RAID-0 since macOS has that built in, but I trust SoftRAID more and the performance is better. Software RAID avoids locking you into a single vendor. e.g, the drives on the Pegasus use a proprietary format and can only be used in another Pegasus box unless you reformat them, which obviously wipes out your data. If any of my SoftRAID boxes fail or if I just want to switch brands, I can put the drives in any other RAID chassis and the data stays intact.
The problem with RAID-5 is it costs storage efficiency (e.g, 6TB usable for 8TB capacity), costs write performance, and during the lengthy rebuild phase all performance can be very slow. In some cases this means you don't practically have non-interrupted service because I/O performance degrades so much it's not usable. With a redundant array you can be up and running at full speed in minutes, albeit at the cost of a little lost data since the last time the arrays were synced.
Another issue with RAID-5 (or any redundant RAID format) is the "sibling failure" phenomena. If one drive in a RAID box fails, there's a greater likelihood of another drive failing since they are often from the same manufacturing batch, operate in common environmental conditions, and have the same operating life. This is a personal preference but if I have one drive in a RAID box fail and they are over three years old, I usually replace them all.
There is a theoretical problem with a single-drive failure on RAID-5 and having a 2nd drive fail during the rebuild phase, but several of the articles discussing this used flawed statistics based on a misunderstanding of bit error rates. IMO that's not a major reason to avoid RAID-5, but there are other reasons.
You could use two 16TB G-Tech GRAID boxes -- one primary and one backup, both in RAID-0, and they only cost about $850 each. They are about 2x the performance of the Lacie since they are RAID-0, and your usable storage would be 16TB:
https://www.bhphotovideo.com/c/prod...ogy_0g04097_g_raid_thunderbolt_2_usb_3_0.html
RAID-0 obviously isn't ideal from a reliability standpoint but even RAID-5 must be backed up. If it's backed up to a similar array, IMO you may as well use RAID-0. You also must consider the business cost of recovery time. If you have good backups to a slow device and it takes 24 hr to restore them, that might be too costly.
That said, an alternate approach is using a faster, more expensive primary RAID box and a less expensive one either for off-line backup via Carbon Copy or on-line backup via Time Machine backup. E.g, 16 TB Thunderbay 4 in RAID-0 and a 16TB G-Tech GRAID for backup:
https://www.bhphotovideo.com/c/prod...ting_owctb3ivt16_0s_16_0_tb_thunderbay_4.html
However there's not that much price difference between them, but the OWC is much faster if configured as 4 x 4TB in RAID-0. Having twin arrays means they are both fast and can be interchanged. The Thunderbay 4 arrays I have are not as quiet as the Pegasus2.
I personally always have three different backups for active data: continuous backup via Time Machine, nightly off-line backups via Carbon Copy, and off-site backup for the original media on separate drives.
Re your previous issue with slow 4k H264 FCPX encoding on the nMP, the iMac Pro is much faster. However a top-spec 2017 iMac 27 is also much faster, but it's not as quiet as the iMP.
