Bootable Disks - a couple of questions.

I use Intel Macs so YMMV but in my limited experience new Silicon Macs behave about the same.

> can I set up different partitions and make one partition a "bootable disk"?

Yes. An old-style partition or usually preferably a new-style volume works usually better ("blessing" a cloned bootable volume does not work inside the same APFS container at least in Carbon Copy Cloner while it works if the target is a partition. But volumes are much more handy so I don't use partitions).

> would you see a selection of each partition if you have to use the bootable disk?

Yes via Option-boot. Startup disk panel might not show it.

> can you just ignore the internal hard drive altogether?

I usually unmount internal disk and other volumes so I don't accidentally mess with them. I mount then if necessary.

> If I get a new external disk for a mac studio using Apple Silicon, and Monterey

I use Intel Macs and Monterey and have only a limited experience about Silicon Macs so YMMV. There are external boot problems with Silicon Macs with some enclosures.

So, If I get a new external disk for a mac studio using Apple Silicon, and Monterey, the formatting options are to add one or more containers, and then to each container I can add volumes, so I could have a bootable disk on one container, and Time Machine in a separate container that can have a volume for the Time Machine, and a volume for User Files; or something like that?

If you want to put Time Machine on a separate volume and use the other volumes for something else, you have to create the Time Machine volume with diskutil (assuming they haven't fixed the problem in Disk Utility).

New Time Machine backups want the entire disk, but you can split it with a Container, or a Volume (as per above).

I created multiple boot volumes on an external SSD for an M1 Mac just top work through the process.

My belief (unconfirmed) is that you must create the external boot drive on that particular Apple Silicon Mac because of the way it handles external boot security. The approval to boot from that particular drive is actually written to the drive itself.

Barney-15E wrote:

So, If I get a new external disk for a mac studio using Apple Silicon, and Monterey, the formatting options are to add one or more containers, and then to each container I can add volumes, so I could have a bootable disk on one container, and Time Machine in a separate container that can have a volume for the Time Machine, and a volume for User Files; or something like that?

If you want to put Time Machine on a separate volume and use the other volumes for something else, you have to create the Time Machine volume with diskutil (assuming they haven't fixed the problem in Disk Utility).

New Time Machine backups want the entire disk, but you can split it with a Container, or a Volume (as per above).

I created multiple boot volumes on an external SSD for an M1 Mac just top work through the process.

My belief (unconfirmed) is that you must create the external boot drive on that particular Apple Silicon Mac because of the way it handles external boot security. The approval to boot from that particular drive is actually written to the drive itself.

How to create multiple volumes in external SSD? Is it possible that volumes can have different formats like fat, exfat, apfs? Can we make any volume as bootable? I am having MBA M1 2020 with Monterey 12.6

In Disk Utility you just click Add Volume to add volumes. You then pick the desired volume from the installer. For High Sierra, it must be the first install as the installer won’t recognize other volumes. No problem after that. The Studio can likely only boot from Monterey or later.

All volumes must be APFS as that is the only file system with volumes.

You can add other file systems by partitioning. All APFS volumes can be on same partition, but the other file systems would need to be on their own partition. The partition table must be GUID for APFS, but that should not present a problem for the FAT systems, but could be problematic for some old devices that only understand MBR.

It is a bad idea to use a backup drive for anything else except backups. By using a backup drive for multiple purposes you increase the risk of something going wrong with the drive & volumes. A backup is meant to be there in case of emergency so you want to minimize the chances of something causing the backup from becoming damaged or corrupted.

Plus, what about the data on the other partitions/volumes of the "backup" drive? Backing up data from those other partitions/volumes to the backup partition makes no sense since if the drive fails or becomes damaged, then both the data & the backup are lost at the same time since they are stored on the same physical drive.

In addition, people usually realize much later that one or more of the multiple partitions is too small which then requires erasing the whole drive and starting over which requires lots of time and moving lots of data around. Get at least one dedicated drive for your backups, and another drive for any other uses (bootable external, or external data drive). Using multiple APFS volumes within a single Container is different since each APFS volume within a single Container shares the full storage space of the Container. However, backups should be stored on their own dedicated drive and should not be shared with a bootable OS or data drive.

With M1/M2 Macs with Apple Silicon, you will need to install macOS to the external drive if you want a bootable external drive. Previously it was possible to make a bootable clone of the internal drive, but beginning with macOS 11.x Big Sur the new security features are making bootable clones very difficult if not impossible. A respected developer of one of the cloning apps has already mentioned that bootable clones are a thing of the past on Macs and currently is a "best effort". There are multiple reports on these forums where a recent macOS Monterey update may in fact prevent the creation of bootable clones on M1/M2 Macs with Apple Silicon.

https://bombich.com/kb/ccc6/cloning-macos-system-volumes-apple-software-restore

You should always have frequent and regular backups of your computer and all external media (including the cloud) which contains important & unique data.

You really, really, really don't want to use an external boot drive on a modern Mac.

Can you explain in more detail exactly what problem you are having? The only thing I can say for certain at this point is that an external drive is not the solution. The only time I recommend external boot drives are on 2017-era iMacs with failing internal mechanical drives.