Time Machine backup redundancy?

With Time Machine, you can have two or three or more backup drives. Time Machine simply cycles through them in order so you have redundancy. If you use three such drives, for instance, no backup will be older than 3 hours in the past.

With a different type of backup to supplement Time Machine, such as SuperDuper (which I use, or Carbon Copy Cloner, which also has an excellent reputation), you have an additional type of redundancy, namely the fact that SD or CCC use a different method for making the backup than TM. So if through some mishap your Time Machine configuration on your Mac got corrupted (this has happened, albeit rarely, to some users), preventing recovery from the Time Machine backup(s), your other SD or CCC backup, which is basically a bootable "clone" of your drive, provides a separately made backup copy of all your files.

I typically have two Time Machine drives for each Mac plus a SD backup. One Mac in fact has two SD backups which I alternate between. This may be a bit overkill, but no one ever has suffered from having too many backups, but many have suffered from having not enough backups. Many try to store one backup "off site" in case of fire, theft, etc.

Another method involves cloud-type backups, or at least copying critical files to cloud storage repositories such as Dropbox, Microsoft, Google cloud storage, etc.

You definitely should have at least two backups, and I suggest disconnecting one from the Mac when it is not in use. For instance a severe power surge or lightning strike could disable both your Mac as well as any drives connected to it. So the additional backup that is physically disconnected (or somewhere in the cloud) might be important to have someday.

Hi,

In addition to TM, I backup to a second drive using Carbon Copy Cloner, so in addition to two backups, I have two different types of backups. Obviously I recommend a setup like this. You could instead use SuperDuper! or another Mac cloning app.

You can have Time Machine backup to multiple drives rotating between each drive ever hour.

in your case at most one drive is 1 hour behind the other drive as being up-to-date.

Not a bad approach.

Using a different backup utility gives you protection against bugs in the other backup utility. Also if the 2 alternate backup is bootable, you can boot from that drive if you need to get to work right away, and restore the internal when it is convenient.

Both approaches are valid.

Time Machine when physically attached to a Mac that does not move, is very stable.

The problems with Time Machine happen when used with network storage and the user just closes the laptop lid, and leaves the building. Or if physically attached, and the user unplugs the drive without cleanly unmounting the drive before unplugging.

in those situations Carbon Copy Cloner is more robust.

I use multiple backup approaches. Time Machine for my company desktop Mac system alternating between 2 USB attached backup drives. But I also run SuperDuper once a day on that system. SuperDuper is a similar, but different backup utility to Carbon Copy Cloner.

On my personal laptop, I have Carbon Copy Cloner backing up to a Synology NAS over WiFi. The Synology is itself backed up to another Synology in another location.

I do not use the Synology with the company Mac because it is always VPN connected to work, which blocks access to my local LAN and the Synology NAS.

Ok, I was going to suggest an SSD might be worth considering as CCC or SD would realize significant backup speed increases if you went the cloning route, but the capacity you're working with probably contraindicates an SSD setup.

I believe CCC is more reliable than TM. There are plenty of posts about people having issues with TM backups.

You're welcome.

How big is your iMac's internal drive and how big is your TM backup drive?