[Avid-L2] Mac local storage for Avid media recommendations

Looking for some local storage recommendations for a trashcan Mac.  We got a G-Tech Shuttle XL 

https://shop.westerndigital.com/products/external-drives/g-technology-g-speed-shuttle-xl-thunderbolt-2-hdd#0G04651

And it is just terrible.  I mean if I'm doing a finder level copy of a ton of data it's very fast, but as media storage it is just very slow to respond and scrub a timeline or clip.  This is comparing it to an identical MacPro with the same project and media that's on an ISIS.  The systems are being used as offline editors with DNx LB media, so the bandwidth isn't huge.  But it does need to be 30TB+ because the it's going to mirror the ISIS, just in a remote location.

Thank you for your recommendations.

Jay