Trying to understand Time Machine backup structure

[Top19]

I am trying to figure out what constitutes a full Time Machine backup. I want to backup my Time Machine backup for my 500 GB (400 GB are being used) Mac to the cloud. There are quite a few folders / backups on my external hard drive that serves as my Time Machine, so I'm not sure what should be backed up and what can be left behind. All I want is the most recent full backup. Something that works by itself and doesn't rely on any pointers or other snapshots / backups.

Here is a screenshot of my Time Machine backup drive: http://imgur.com/a/sdABD

Can I just backup the folder titled "Latest", or perhaps one of the folders from October 3rd? Will that be enough in case I need iDrive to ship me a drive with my data back in order to do a restore?


Thanks all,
Top19

 

[MacInWin]

That is not how TM works. On the FIRST backup of a set, TM does a full backup. At the next backup, it checks for files that have changed and only copies them to the backup, but creates symbolic links to the original backup for the unchanged. On the second backup, it checks for files that have changed and copies them, then creates symbolic links to the symbolic links of the second backup that are unchanged. Lather, rinse, repeat.

So, there is no "most recent full backup" in the sense of a complete set of backups. If you want it to "work by itself" you need the entire backup set, i.e., the entire drive.

Now, to get a "recent full backup" you can always force TM to start over, but then you will have lost the archive of older files. Or you can use a cloner like Carbon Copy Cloner or Super Duper! to make a full clone of your drive.

 

[ferrarr]

If you only want what is currently on your "Mac", use another external drive with Time Machine and make it start over. Or, you can erase all your current Time Machine backups and use your current external.

Why not just let iDrive backup your computer and keep your Time Machine going?

 

[chscag]

All I want is the most recent full backup. Something that works by itself and doesn't rely on any pointers or other snapshots / backups.

Then you don't want Time Machine. Use Carbon Copy Cloner or SuperDuper as has been suggested. And since you're already subscribed to iDrive, you have a certain amount of redundancy in case all other backups fail. Time Machine backups are not bootable where as Carbon Copy Cloner and SuperDuper cloned backups are.

 

[MacInWin]

chscag, I have always though TM backups wouldn't boot, but then ferrarr pointed out this:

https://support.apple.com/en-us/HT201250

At the bottom of the article is this:

In OS X Lion v10.7.3 or later, you can also start up from your Time Machine disk, if necessary. Hold down the Option key as your Mac starts up. When you see the Startup Manager screen, choose “EFI Boot” as the startup disk.

That seems to imply you can boot from a TM backup. I've not tried it, nor have I ever heard anyone who got it to work, but that's what Apple said.

 

[Slydude]

I'm going to have to take a look at this and maybe discuss it in a future show. I always thought that all the documentation said you could not boot from a Time Machine backup. I'm pretty sure it was true in the initial releases of Time Machine.

That support article certainly implies that it's possible to boot from a Time Machine backup following their procedure. I can't tested at the moment because my Time Machine backup is all my Time Capsule and I'm not sure that this will work over a network. I don't think it would.

 

[chscag]

Likewise I have never heard of anyone who got this to work right. An EFI boot would indicate to me that the EFI partition was intact on the Time Machine disk, otherwise how would an external drive with no bootable partition boot? I've looked at my Time Machine external drive and do not see an EFI partition. Also, an EFI partition is formatted as FAT-32 whereas the entire Time Machine external drive is formatted as HFS+.

The only way it could possibly work is if the process uses the EFI partition already located on your internal hard drive or SSD to boot from and then uses the Time Machine data to progress. That probably will work. But what if your hard drive is toast or corrupt? Interesting stuff. ;D

 

[Slydude]

I agree Charlie. That would work if the recovery partition on the boot drive is intact and should work if the EFI partition is intact. If the drive is completely toast I don't see how it would work. It's one of the reasons I've continued to suggest cloning even though Time Machine has improved since its initial release.

 

[ferrarr]

I think you are all correct. I just tried, and after selecting Time Machine, the macOS Utilities screen come up, just like when booting from Recovery. So, you have all the regular Recovery options, Restore TM, Reinstall OS, Online Help, and Disk Utility. I won't go any further, I just wanted to test the waters.

 

[MacInWin]

So the bottom line still is that TM Backups cannot be booted, but clones should. But IF (and there is no guarantee), there is an EFI partition on the TM drive, it may be possible to boot sufficiently well to restore from that backup. I can live with that...

 

[Slydude]

Let's assume for a moment that someone doesn't want to run one of the cloning apps. I think that with a little bit of preparation a Time machine backup could be made "relatively bootable" and about as reliable as booting from a clone. Here's what I think would do the job:

1. Partition the drive you are going to use. The boot partition can be relatively small since it will contain only a minimal OS)
2. Install a minimal version of whatever operating system you are using (Yosemite, El Capitan, etc).
3. Select the second, larger, partition as the destination for Time Machine backups.

With this arrangement you can boot from the primary partition by holding down the option key and selecting that partition. Once the bootup is complete you would have access to your Time Machine backups to restore everything. I think this would work but it's been a while said I since I tested anything like this.

 

[MacInWin]

Sly, that's a very good approach. Still can't boot from the TM backup PARTITION, but you can boot from the DRIVE. You don't get back in operation as fast as booting from a clone, but at least you can recover.

 

[chscag]

Actually what Sly proposed above is what's recommended by many Mac pundits who are in the know. Sly used to write for a web site that was Mac oriented so he's pretty good at that stuff.

Off topic alert.... Speaking of boot, I wish we could "boot" a certain presidential candidate! (I had to say that after absorbing all the BS this past weekend). ;D

 

[Slydude]

Actually what Sly proposed above is what's recommended by many Mac pundits who are in the know. Sly used to write for a web site that was Mac oriented so he's pretty good at that stuff.

Thanks Charlie. I actually enjoyed writing for them--except for the months here and there where I had difficulty thinking up topics for columns. I took the link out of my signature recently because somewhere along the way it became impossible to search that site from the main page. Much like here, there were some very knowledgeable folks involved in that project.

As a result of writing for them I learned three things that usually help me when answering questions in the forum:
1. Sometimes when you are trying to explain something to a user you've never met it's difficult to get the level of complexity right. Too simple and it sounds condescending and too complex simply frustrates the other person.
2. Sometimes I go waaaay overboard when answering a question. If you want proof of that see this article. What started as a simple question from a reader morphed into 3 Automator workflows and an AppleScript.

 

[ferrarr]

Thanks Charlie. I actually enjoyed writing for them--except for the months here and there where I had difficulty thinking up topics for columns. I took the link out of my signature recently because somewhere along the way it became impossible to search that site from the main page. Much like here, there were some very knowledgeable folks involved in that project.

As a result of writing for them I learned three things that usually help me when answering questions in the forum:
1. Sometimes when you are trying to explain something to a user you've never met it's difficult to get the level of complexity right. Too simple and it sounds condescending and too complex simply frustrates the other person.
2. Sometimes I go waaaay overboard when answering a question. If you want proof of that see this article. What started as a simple question from a reader morphed into 3 Automator workflows and an AppleScript.

And # 3 is?

 

[Slydude]

Oops. Guess we know why I'm not an accountant.

#3. There were lots of times I didn't write an article because it seemed to simplistic / common knowledge. I'd later discover one of the editors thought it was a good idea and wanted that article written. Common knowledge for one person is virgin territory for someone else.