Partitioning a Fusion Drive for dual boot

[Vosie]

I'm wanting to partition my 1.12Tb Fusion drive on my (late 2012) iMac i7 3.1Ghz, 8Gb Ram, 21.5 inch, 10.14.6 (I will update to 10.15 when stable update released) - so dual boot to 10.14/15 or 10.8.

I'm wanting to put an older OS like 10.8 on the new small partition to run older software better (Adobe CS4 and COD 4)

- Will partitioning the 1.12Tb Fusion Drive degrade performance of either boot-up
- Do both partitions take advantage of the SSD portion of Fusion Drive or will the new partition only be on the 'platter' or 'rotational' part of the Fusion Drive.

Cheers

 

[Fishrrman]

I could be wrong (and others will correct me), but...

If you want to partition a fusion drive, I believe that the only choice that disk utility gives you is a 50/50 split. And the portion of the fusion drive(s) that actually "gets partitioned" is the HDD portion.

So if the object is to have a second OS on the second partition, be aware that it's going to reside entirely on the HDD portion.
That means... SLOW operation.

Want a better option?
Buy a small SATA 2.5" SSD -- you can get a 120gb drive for about $20.
Put it into a USB3 2.5" enclosure -- about $10.
Install your "secondary OS" onto that.
It will run much, MUCH faster than from a partitioned fusion drive!