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Does make sense to use Time Machine with external drive if I already have all my files stored in iCloud? What laptop information is Time Machine keeping that cannot be stored in iCloud?

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    The clue is in the name: multiple copies of last hour, last day, last week, last month.
    – benwiggy
    May 17, 2021 at 11:40

6 Answers 6

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Time Machine can, in theory, restore the exact state of your Mac at any time. All apps, prefs, settings, documents.

iCloud will restore only your documents. Everything else would need to be re-installed from scratch.

Whether or not you consider that 'necessary' is your call.

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    Time machine also has hourly, daily, and weekly backups going back as far as possible (until it can't store any more snapshots). In general, iCloud only stores the current state with very limited timestamped backup capabilities, although some iCloud Drive apps do have version control on documents they edit. May 17, 2021 at 18:45
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    And, of course, iCloud is not a backup (it’s a synchronization tool, which you can use like a backup or as part of a backup solution, but the real-time sync means it is very much not a backup by itself), and even if it was it’s controlled by a third party and thus subject to potential limitations on availability when you go to restore files. May 18, 2021 at 2:15
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    Good answer. I would add that bandwidth is also a big difference. Many people using cloud-based backup systems realize how slow restore is after a disaster. Using TimeMachine on a external drive will make the restore process many many times faster. May 18, 2021 at 6:52
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    Belt & braces. I use both. Time Machine for, 'oops, my drive died' or 'what did I do with that file?' & Backblaze for 'dammit, my house burned down'. I use iCloud to sync my keychain & not much else.
    – Tetsujin
    May 18, 2021 at 6:59
  • @AustinHemmelgarn back blaze is also controlled by a 3rd party, but it’s certainly a backup and I think it probably has better availability than a single hard drive sitting next to the computer it’s backing up
    – Tim
    May 19, 2021 at 0:12
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Yes Time Machine is needed even if you have iCloud. iCloud is not a backup system it is synchronisation.

Time Machine makes a copy of your file so it is in two places and if you delete one then the other is still there

iCloud makes the file available in several places but if you delete it in one then it is deleted in all places.

Also Time Machine copies all files on your disk and iCloud only syncs a few folders.

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  • iCloud offers versioning. So even once “deleted” it isn’t truly deleted - and likewise for overwriting files.
    – Tim
    May 17, 2021 at 21:52
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The key is the difference between a copy and a backup.

iCloud Drive is essentially an off-site copy of your data. That’s great — if your house burns down, you still have your files.

But it is not a backup of your data. Because if you were to (accidentally) delete a file from your iCloud Drive and then immediately have your house burn down, the file has gone forever.

The main property that backups have that a copy does not is that they can go back through time. Let’s say you edit really important file.txt and make a terrible mistake, but you don’t realise for a while what you’ve done. Next week you open it up and realise your mistake.

iCloud Drive doesn’t help you here: the mistake you made has synchronised to the cloud. But your backup has a version of the previous file that you should — depending on available space and your defined backup rotation scheme — be able to go back and retrieve.

Similarly in the case where you deleted a file and then your house burnt down, a backup that didn’t burn down along with the house will allow you to retrieve that file. (Point 4 below solves for this disaster. You could also store your Time Machine drive in the shed, at work, etc.)

Ideally you should combine these technologies. The maximally ideal state is one where you end up with:

  1. A ‘local’ copy of your files that you work on every day. This is just your Mac.
  2. An off-site synchronised copy of your files that you can retrieve very quickly if your Mac is offline, or that you can use for convenience, e.g. accessing your files from your iPad. This is iCloud Drive.
  3. A local backup of your files that you can use to restore from very quickly. This is Time Machine.
  4. An off-site backup of your files that you can use when your life goes terribly, terribly wrong. This is the ultimate insurance policy; you hope you’ll never actually need to use this. Something like Backblaze.
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  • Indeed. A burglar can steal your mac + external drive, a fire can burn your mac + external drive, a "backup" done in the wrong direction can delete files on your system, and so on. Point 4 is really needed. May 18, 2021 at 20:22
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When planning your backup, you should always think about the worst-case scenario, and Time Machine can definitely fail (here's just one example among many).

Time Machine doesn't contain a clone of your system. It merely hopes to be able to restore a clone of your system, by applying incremental backups one after the other and by juggling with non-standard hard-links for folders.

So iCloud + Time Machine is not a sufficient, reliable backup strategy. You should have a real clone on an external drive, and this drive shouldn't be in the same location as your computer and Time Machine drive. (See 3-2-1 rule)

One advantage of using a complete clone (e.g. with Carbon Copy Cloner, among others) is that you can boot from it and check if everything works fine. With Time Machine, you typically only run a restore when you really need it.

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    @Tetsujin From the linked article : "You can also only hardlink files and not directories." What's non standard in Time Machine is that hardlinks are used for folders, and not files. May 18, 2021 at 14:05
  • I am sure you can find reports of restore from CCC failing as well. However I do agree with the overall point all software fails and you need multiple backups. SO don't criticise Time Machine here. I have TM CCC and offsite. In Big Sur with AFDS you do get a clone - or a snapshot.
    – mmmmmm
    May 18, 2021 at 16:29
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    @mmmmmm: There's a huge design difference between CCC and TimeMachine, though. If one file is corrupt on the CCC drive, you might lose one file. If one file is corrupt on the TimeMachine drive, you might lose the whole backup. I've seen it happen 3 times already. See apple.stackexchange.com/a/396979/290295 for more info. May 18, 2021 at 16:33
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    I suspect that TM on APFS now does that as it does snapshots. I agree that on HFS+ and even more on a sparse bundle TM is not reliable
    – mmmmmm
    May 18, 2021 at 16:39
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iCloud is not a backup. Apple tells you it is not a backup. There is no way to easily backup files that are kept only in iCloud.

So if your data doesn't actually matter... sure, keep it only in iCloud.

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    Disagree. It's like saying that Dropbox is not a backup, but in reality, if I have my files on Dropbox (very much like iCloud Drive) then I drop my laptop in a fire, I'll still be thankful that I have a secondary copy of those files in iCloud (or Dropbox, or any other file synchronization service), ready to download onto a new computer. The other answers noting that iCloud doesn't store applications nor system settings still is an important difference between Time Machine and iCloud. May 18, 2021 at 18:24
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You don't need either Time Machine or iCloud.

For backup:

  • You can use an alternate means for network backup: I use Carbonite for instance.
  • You can just do "plain old" on-site backup. I use 'rsync' set up by custom perl scripts to iterate on each drive, manage exclusions, etc.

For version control:

  • You could do that "old school" by rotating backup "tapes" (USB sticks), like we used to do with exabyte tapes and servers. You have a daily rotation of typically 5 tape sets... then at intervals you pull one of those out as a quasi "monthly" and just store it forever. Just as well, since the tapes had limited life. Do that with USB sticks. I would note: back then, nobody could hold a company hostage by "ransomware", you would just bag the hard drives for evidence, slap in new hard drives, and restore from a sufficiently old backup.
  • You could use somebody else's versioning software.
  • You don't need to use versioning backup at all if you don't want to.
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  • Sure, it's possible to do it this way. It would be a good idea to not rely completely on DIY solutions, though, because maybe the corresponding scripts are buggy, and a "backup" done in the wrong direction could clone an empty drive to your system, for example. May 19, 2021 at 10:17
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    I caution against recommend rsync for backup for the average joe. Unless really people know what they're doing, it's remarkably easy to make a "back up solution" that does an incredible job of destroying all your "backups" (naive duplicates) after a ransomware attack.
    – Alexander
    May 19, 2021 at 15:13

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