I have the development beta of macOS 10.13, however I cannot install the upgrade because of the SSD RAID 0 I set up earlier this year to increase R/W speeds. The exact error message from the installation utility is "You may not install to this volume because it is part of a AppleRAID."
It is a software RAID done through Disk Utility on a MacBook Pro 9,2 with 2x Crucial MX300 275GB SSDs. I remember I had to create two separate partitions from each of the two drives, and RAID two of them together as a main drive and the others as a recovery drive in order for the operating system to install.
I am currently running Sierra, and the only other modification the laptop has is a memory increase (4GB to 16GB).
I would like to preserve my files in the same fashion as a regular installation of a new OS onto a single drive system. What would be the easiest way to do this? I have access to two 1TB hard drives I could RAID together to use as a backup system, and do a clean installation of High Sierra, and then transfer over the files from before. This is a bit tedious, and I am unsure about how to do this with a beta software which can't be pulled from the online recovery system during startup. So, if there are any more convenient ways to go about this issue, I would really appreciate the advice. Thank you!