From what I found, if you want to use Time Machine, it has to be APFS, regardless of drive type. I’m not sure on drive speeds, but as a backup drive, I’m not to bothered.
Is there a reason you have in mind leading you to use HDD vs. SSD?
Personally, I would never put those three things onto the same drive, partitioned or otherwise, HDD or SSD.
Lose the drive, or the drive fails. and all three are gone.
I use the so-called 3-2-1 strategy: make at least three copies of all your data, backed up on two separate media, one of which is offsite.
I default to using APFS on spinning drives and SSDs, and it has been quite reliable for me.
The OWC guy picks on it, but doesn’t answer challenges to his thinking or data collection methods, so I don’t give his opinion any weight.
I suggest using APFS. If the backup program you like wants something else, then use whatever it chooses.
As @anon41602260 said, I wouldn’t mix and match on the same drive. Dedicate a drive to being a backup (using one backup program) and nothing else.
Also, I wouldn’t rely on Time Machine. It runs for 6-8 months for me, then loses its mind and needs to start over. I stopped using it entirely a couple of years ago. I use Arq 7 for my hourly backups to an external drive, and to my NAS. It also does a weekly backup to my hot, noisy old Dell server that I turn on once a week. I use CCC to make a monthly backup to a cheap external drive. I have two of them and alternate. I also have Backblaze always running in the background.
Oh, I also back up my Windows machine, my MBP and my girlfriend’s MBP to the NAS using Arq. Version 7 has been reliable. Version 5 also served me well for 4 years. There were problems with Version 6, so I skipped that one.
I agree with @JohnAtl, Time Machine is unreliable. And since the changes Apple made to macOS has left Carbon Copy Cloner unable to create bootable drives it has lost what I considered to be its key feature. So, of the three, I would recommend ChronoSync. Solid software and free upgrades for life. @anon41602260 ‘s suggestion of a 3-2-1 would be my choice.
I’ve not had any problems with APFS although it seems to slow down spinning drives more than HFS+, ExFAT, etc. But that shouldn’t be a factor with Chronosync after the initial backup. So take your choice.
This is one situation where it does make sense to have both a belt and suspenders …
I’ve been using Time Machine pretty much since it came out. I guess I’m lucky as I’ve never had an issue. This past summer (northern hemisphere) our house took not one but two direct lightning strikes, about a week apart. Which fried, among other things, my Mac mini. I got a replacement, and used the last Time Machine backup to restore everything.
I also use BackBlaze and had them send me a hard drive of my system backup just in case. I did not need it. But had the Time Machine drive also been fried it would have been a lifesaver. Like I said, belt and suspenders.
Photography is one of my hobbies, and I use Chronosync to keep a local backup of my images (which are also backed up with Backblaze). One of my image drives was working but having issues (sometimes it would mount, sometimes it would mount but show no files, some times it wouldn’t mount). Fortunately I had local and offsite backups, and after buying a new drive, replaced the dying one (also because of the lighting strikes).
And for historical reasons I also have SuperDuper, which I use for making bootable drives.
So that’s my three copies:
The live files on the working drives.
Time Machine, Chronosync, and SuperDuper (I really could consolidate here, but it is working so …) as my local backups.
Backblaze for off site.
And I use a mix of HDDs and SSDs based on the amount of data to backup. So the local system drive backup is to a SSD while the image files are to HDDs. Mainly because of cost.
So to answer your question, the best way forward is to determine your backup strategy and then pick the software and hardware to achieve that. The products and services mentioned in this thread are all good ones, and as you note you already own/use some.
From what I understand, Time Machine makes snapshots on my data drive and you can’t turn that off. Does Arc7 just back up to your desired drive w/o making snapshot on your local drive. I don’t want snapshots on my local drive.
Should I be concerned with the number of times snapshots are written to the internal SSD, whether using TM or Arq 7 (re: educing the lifespan of my SSD)?
No, nothing to worry about.
My understanding is that the number of writes to the disk is not significantly increased, the snapshot is just hanging onto the pieces of files that would have been overwritten. So the writes that would have happened anyway are just happening to different places on the disk.
I was just trying to cover all possibilities of failure. For example if some flaw was discovered in CCC, I would have Arq backups, and vice-versa. CCC also used to make bootable backups, but later versions of macOS don’t allow that.
At one time, I had gone a little overboard with backups. In my defense though, it was a good thought experiment, trying to think of all vulnerabilities.
I turn the hourly snapshots off in Timemachineeditor. Backups to Time Capsule every four hours and daily and weekly backups to external drives via Carbon Copy Cloner are enough for me.
That’s quite a statement. If anything at all a backup programme should be reliable, that’s the whole point. It’s as concerning as someone handing me a parachute and telling me it might work.
Is this a consensus opinion? I’m only using Time Machine for all my backups.
I definitely wouldn’t do that, not with any backup program.
And I assume you have a cloud backup, like Backblaze, or something offsite at a bank, etc.?