iMac Pro seems to underperform on reading & writing large files  



I'm working with a client with a 2017 iMac Pro running 10.14.6. It's got a 3 Ghz Intel Xeon W Processor, 64GB RAM, and a 1TB SSD. 

He works with gigantic photography files and bought this machine for that purpose. I'm currently testing photoshop where he's got a 15GB large document format (psb) file open. As a simple test we are saving a new copy of the file in photoshop to the desktop. The drive is rated at about 2.5-3 GB/s read and write speeds, and as I write this it has saved only 29% at the 6 minute mark (38% at the 8.5 minute mark). If my math is correct the whole file should be done in 5-10 seconds tops?

Took it to Apple and they were unable to determine any issues during their diagnostics, and simply wiped the machine and sent it back. We now have a vanilla copy of Mojave on here with basically nothing installed except for Photoshop CC. 

Is there any recourse? What could be wrong? Please advise fellow geeks1



Start by running Blackmagic to see what the write speed is
If the write speed is close what is expected, then your assumptions about what Photoshop is doing when saving a file are the in agreement with what Photoshop is doing.
I'm not a Photoshop user, so I cannot tell you if this is normal or not.

@datafornothinandbitsforfree I'd already checked Blackmagic and speeds are writing as expected that way.

Anyone here know if this is normal for Photoshop to take this long?


Have you checked the Adobe Photoshop Forums? You might get more feedback over there. I've used PS to work on big files, but not 15 GB, that's extreme. How did he set up his memory handling in PS? if you allow 80% of RAM and you have only started PS, then you should be able to get that 15 GB file in RAM easily. IF you have changed the defaults and/or have started Mail, safari and a bunch of other apps before launching PS, then PS gets 80% of what is actually available, not your total RAM. Here's the PS forums