Thunderbolt drive and High Sierra

QIf I upgrade to High Sierra, will my iMac still be compatible with my Promise Pegasus R4 RAID, which contains my backups?

AYes, provided that you’re running current versions of the drive’s software, and that you update the drive’s firmware.

Before upgrading to High Sierra, visit the Promise support page at promise. com/Support/downloadcenter. Select Legacy products, then model details. Download the Pegasus Series Utility for Mac and the Pegasus Series Driver for Mac, and install them.

It’s worth installing the driver, which is a kernel extension, before upgrading to High Sierra, as that version of the system handles third-party extensions differently, requiring an additional authorisation step in order to use them.

With that new version of the Pegasus Utility installed, you should be able to upgrade its firmware directly from within the app, although older versions sometimes caused problems. If you do have issues, download the firmware from the support page and install it using the Firmware Update command from the utility’s Admin menu, as detailed at bit.ly/firmprompeg.

Once your RAID drive is fully up to date, proceed with the High Sierra upgrade. When that’s complete, it should be safe to leave Time Machine backups turned on, as is the default, provided that you don’t restart your iMac in Sierra. That often wipes out the database which Time Machine uses to determine what to back up, and may well force a complete backup of your iMac’s drive, as if performing an initial backup. If you have a Thunderbolt RAID array and you’re thinking of upgrading your operating system, visit the manufacturer’s website and download the latest support software for your drive.