Mojave requires APFS as the default format. Case in point is if you have a mechanical hard drive and want to upgrade to Mojave. Please keep in mind that later OSes were not developed with older hardware in mind, meaning older hardware gains no benefit from a newer OS. hardware/software they want to run requires it, or because they want to. I run both Mojave and Catalina on it and Mojave (final OS) and High Sierra on my cMP 2009 (12-core 3.33GHz with 48GB RAM, 8GB VRAM, and NVMe boot blades that are about 10X faster than an SSD in a drive bay )Ĭlick to expand.If you have to ask someone else if you should, then you have no need to. Catalina is probably your last OS anyway as I know that's the plan (unofficial) for my 2012 MBP. A full, clean install with apps is only about 30GB, but you need another 20-30GB for the OS Swap File. I would say 64GB would be enough as long as you put all data elsewhere. I don't know if the tiny SSD packed with the 1 TB Fusion is big enough. I did that to a 2015 iMac with a 3TB Fusion drive and a 120GB SSD, and she just upgraded to Catalina without problems. If you want to run the latest OSs, just separate the Fusion drive into its separate parts. There are some nice abilities of the newer OSs, but nothing earthshaking. I know several people still using High Sierra due to tethered shooting with an older medium format back. I agree with previous poster, but I'd say that don't go past High Sierra as there are problems with using a fusion drive with APFS which is required for booting in Mojave or Catalina.

High sierra catalina