#External boot drive mac ssd software

#External boot drive mac ssd software

Your first task, once you have rescued any software supplied on the SSD and saved it to your Mac, is to format the disk in APFS. When supplied, most SSDs come pre-formatted in a cross-platform (read: PC) format. If you want one disk to contain two or more bootable copies of macOS, it is therefore best to separate them into individual containers/partitions, as that allows them to have as many volumes as they wish, for recovery, VM, etc. Although it’s possible to squeeze more than one bootable version of macOS onto a single APFS container/partition, it’s normally preferable to keep them in separate containers/partitions, and that may prove to be essential in Catalina. What used to be a ‘blessed volume’ in HFS+ has now grown to four separate volumes in Mojave, and five in Catalina with the addition of its read-only system volume. The structure and layout of bootable disks has become more complicated with recent versions of macOS and with APFS. a volume shares the space allocated within a single container/partition with any other volumes within it, thus normally has variable size up to the maximum of its enclosing container/partition.a container/partition is a fixed-size division of the disk,.a disk is the top level, the whole storage device, such as your 1 TB SSD,.

In this article, I will only consider working with APFS, and because of the confusing usage of terms, I will stick to the following: Forget that now: APFS is different, as it divides disks first into fixed-size containers (unfortunately referred to in Disk Utility as partitions), each of which then contains one or more volumes. In HFS+, a disk consists of one of more fixed-size volumes, which were often referred to as partitions. Once you have got past the confusing terms and tripwires in Disk Utility, this should prove fairly simple to set up.īefore we get started, it’s important to synchronise terminology, particularly if you’re still more used to using the old Mac Extended file system, HFS+. Sometimes having an external drive that can boot one version of macOS isn’t enough: you want it to boot two (or even more).