As you may have read in my previous post, I’m not an immediate fan of Apple’s newest operating system known as “Catalina”.

Apple has made significant changes under the hood in Catalina. While there aren’t a *lot* of new user features, there are some important differences in what is going on with this new operating system. Here are some things to consider:

32-Bit apps are no longer supported.

Apple has been weaning us away from older “32-bit” applications and utilities for some time now. The messages you may have seen stating that a program isn’t “optimized for your Mac” was their way of saying: “Hey, you just launched a 32-bit app. Future versions of Mac OS won’t run those apps. Update this app ASAP.” Catalina is the first release of Mac OS which will NOT run any 32-bit software. It’s a 64-bit world now.

To check to see what 32-bit software you may still have on your machine:

1. Choose “About This Mac” from the Apple menu
2. Click the “System Report…” button at the bottom
3. Scroll down in the column on the left and choose “Applications”
4. Look in the “64-Bit (Intel)” column for anything listed as “No”. “No” means an app is 32-bit and will not launch under Catalina. “Yes” means an app is 64-bit and will run.

If you still have 32-bit apps you depend on, they’ll need to be updated to 64-bit versions before they will launch under Catalina.

The system volume and user data volumes have been separated.

Until Catalina, Apple installed the operating system on the same volume (disk) as your data. This has some inherent security flaws because it means the entire disk, including the operating system must be “writeable”, and therefore vulnerable to viral, ransomware and malware attacks. In Catalina, Apple installs the operating system on a new, separate read-only volume, meaning only very specifically authorized processes can write to the system volume. This is a large step towards combatting viruses and malware.

The user doesn’t see any obvious signs of this separation of OS and data… until you start working with applications which need to do things like backup or clone your hard drive. Carbon Copy Cloner handles this elegantly, but it can be confusing if you aren’t aware of it.

External backup disks must be formatted as APFS.

With the release of High Sierra (March of 2017), Apple introduced a new file system, known as APFS, replacing the older HFS + (also called “Mac OS Extended”). Oversimplifying, the file system is responsible for managing how files are written to the storage devices (SSD or hard drive) and keeps track of which files are located where. Starting with High Sierra, Apple automatically reformatted an internal SSD as APFS during installation, so you’re probably already using APFS and didn’t realize it. APFS was designed with ultra-fast solid state storage (SSD) in mind and until recently, Apple wasn’t recommending that spinning hard drives be formatted as APFS.

APFS is a “modern” file system, is significantly faster, handles up to 9 quintillion files and has some clever features, including file “cloning” (not to be confused with disk cloning/backup) and “snapshots”. When you duplicate (clone) a file or folder on an APFS volume, the file system is clever enough to not actually duplicate the file (taking up twice as much storage space), but rather makes a “firmlink” or what is, in essence, a “alias” or pointer back to the original file. Snapshots are saved “point in time” states of every file on your disk, allowing for a “restore” back to a previous time/state of the drive. This can be instrumental in a situation where a software update doesn’t go well – you can restore from the previous snapshot.

While these features can be handy, even Apple’s Finder gets confused with the file cloning feature. See the video below for an example of this:

https://www.youtube.com/watch?v=KggyuL8mED0

This can be infuriating in situations where you can’t fit the contents of one disk onto another disk of the same capacity, because the first disk has file “clones” which take up very little space on the original disk, but twice as much space when copied.

Catalina won’t boot from a FireWire disk.

Apple discontinued support for booting from external FireWire drives. For users with legacy backup drives which use a FireWire interface, this can be an issue.

External backup drives for bootable backups of Catalina should be SSD’s.

Catalina requires an APFS volume to boot a Mac. If you’re booting from an external drive (i.e. in a situation where you’re needing to boot from your Carbon Copy Cloner clone drive), it should be an SSD, formatted as APFS. Apple has been uncertain about their support for APFS formatted spinning hard drives. Therefore, backup disks used for Carbon Copy Cloner backups of your primary drive should be upgraded to SSD media.

Sure, some new Catalina features including “SideCar” are cool (use your iPad as an external monitor), but there are lots of new things to be aware of, particularly under the hood. Let me know using the “Contact” box (above, right) if you have questions about your particular environment…

My general advice is to stay with Mojave, unless there is some Catalina feature you absolutely can’t live without. Download link:

https://apps.apple.com/us/app/macos-mojave/id1398502828?mt=12