


If your backup disk is a rotational HDD, however, we still recommend HFS+ for macOS High Sierra, and we're almost ready to start recommending APFS for Mojave users. If your backup disk is an SSD, however, we do recommend that you erase it as APFS. You will get a message saying 'DiskPart succeeded in cleaning the disk'. Having an HFS+ backup of an APFS-formatted startup volume is acceptable that will function just fine for any future restores, even to an APFS-formatted volume. Type select disk and the number of the disk you want formated (make sure that you select the correct one as you run the risk of formating your main drive which is usually disk 0) and hit enter Type clean and hit enter. You don't need to do anything at all to your backup disk after upgrading to macOS High Sierra (or later). If the OS upgrade converted my startup disk to APFS, what do I need to do to my backup disk? Do I have to erase it as APFS? Both APFS and HFS are valid destination formats when using Carbon Copy Cloner 5 on High Sierra (and later OSes). You can choose, however, to erase the SSD as APFS prior to cloning to it. No, neither the HDD nor the SSD will be automatically converted to APFS. " If I first upgrade to High Sierra on an HDD, and then clone to an SSD, will the SSD be converted to APFS? Here are a couple of excerpts from the CCC documentation (page 24): Click to expand.CCC does not change the format of the target drive.
