Time Machine vs Cloning

[Ambrosia7177]

What exactly is the difference between using Time Machine to backup your computer and creating a "clone"?

I have never used Time Machine and don't really understand what advantages it offers over, say Carbon Copy Cloner (CCC).

Thanks.

 

[casperes1996]

Time Machine is itterative, which means it doesn't make a single clone. Instead, it keeps track of differences. Let's say you backup a 300 gig drive. First time, it basically makes a clone in a sparsebundle. Then you delete five files and add 3 new. Time machine will add the 3 files to the backup and keep the deleted files as well, separating the backups by dates but keeping all the old files that still exist in both dates the newer one with aliasses back to the old backup so it doesn't take up 2x the space.
You can extract a single old version of any file or the entire drive or anywhere in between from any moment Tima Machine has been running. You can't exactly just boot from a Time Machine backup though, since the structure isn't really the same as the drive itself. It holds the data but isn't structured like the drive itself, whereas a clone is as the name suggests, for all intents and purposes identical to its source.

 

[Weaselboy]

Just to add a little what @casperes1996 explained so well... by default CCC just does a full clone, but there is an option where you can tell it to keep older versions also. It just dumps those older versions in a dated folder though, so it does not lend itself well to say restoring your Mac to how it was three days ago for example. CCC really is more suited just to make mirror images of the whole disk.

A Time Machine backup can be used to boot to and restore to a new drive much like CCC can, but you cannot actually run the Mac off the TM drive.... it just is used to restore.

Many people use both TM and CCC on separate disks as a double protection backup strategy.

 

[Ambrosia7177]

Time Machine is itterative, which means it doesn't make a single clone. Instead, it keeps track of differences. Let's say you backup a 300 gig drive. First time, it basically makes a clone in a sparsebundle. Then you delete five files and add 3 new. Time machine will add the 3 files to the backup and keep the deleted files as well, separating the backups by dates but keeping all the old files that still exist in both dates the newer one with aliasses back to the old backup so it doesn't take up 2x the space.
You can extract a single old version of any file or the entire drive or anywhere in between from any moment Tima Machine has been running. You can't exactly just boot from a Time Machine backup though, since the structure isn't really the same as the drive itself. It holds the data but isn't structured like the drive itself, whereas a clone is as the name suggests, for all intents and purposes identical to its source.

So it sounds like Time Machine is an "incremental" backup?

Is there a way to configure Time Machine so that it creates a pure clone and then stops?

Is there a way to define what Time Machine backups, and whether it runs or not?

 

[casperes1996]

So it sounds like Time Machine is an "incremental" backup?

Correct.

Is there a way to configure Time Machine so that it creates a pure clone and then stops?

I mean, it won't exactly be a "pure clone" since it'd still be contained within a sparsebundle with folders rather than aan image of the disk, but you can run it a single time and then disable it.

Is there a way to define what Time Machine backups, and whether it runs or not?

Yes. Inside Time Machine Preferences you can add exclusions that Time Machine won't touch. By default it backups everything. You can probably also go the other way around and tell it to only backup a certain set of things and not everything else instead of telling it what not to backup, but I haven't tried that.
Whether it runs or not is also entirely up to you. Automatic backups can be enabled and disabled in System Preferences as well, or through the Terminal. Time Machine has a lot of options in the Terminal if you're into that. The command that controls it, is tmutil and you can read its man page for a lot of tips and tricks.

 

[Ambrosia7177]

Just to add a little what @casperes1996 explained so well... by default CCC just does a full clone, but there is an option where you can tell it to keep older versions also. It just dumps those older versions in a dated folder though, so it does not lend itself well to say restoring your Mac to how it was three days ago for example. CCC really is more suited just to make mirror images of the whole disk.

Do other people really see value in being able to restore your Mac to 3 days ago?

When I am working on something important, like a report, I just save my work as I go. For example, "sales_report_01.doc", "sales_report_02.doc", "sales_report_03.doc" and so on.

Personally, I am more concerned about either needing to restore a recent working copy of my Mac should a drive fail. And it is also nice to have a copy of everything, so I somehow inadvertently delete, say a whole directory full of music!

A Time Machine backup can be used to boot to and restore to a new drive much like CCC can, but you cannot actually run the Mac off the TM drive.... it just is used to restore.

So I could take a TM backup and restore it to a new HDD and it would in essence create a bootable clone? Or am I not understanding you correctly?

Many people use both TM and CCC on separate disks as a double protection backup strategy.

What do you do?

 

[Weaselboy]

Do other people really see value in being able to restore your Mac to 3 days ago?

I've never needed to do it, but I see it used often on here to get back to a previous OS version. Say you upgrade from Sierra to High Sierra and find problems, you can easily roll back to before you installed High Sierra.

So I could take a TM backup and restore it to a new HDD and it would in essence create a bootable clone? Or am I not understanding you correctly?

Yes... if your internal drive died, you could install a new drive, then option key boot to the TM disk, then format the drive and click restore.... and you would be right back where you left off.

What do you do?

I have a disk connected full time that does hourly TM backups. Then every few days or so, I attach a second disk and update a CCC clone. Then I also use the app Arq to backup my users folder online to BackBlaze B2 servers in case the house burns down with my disks in it.

I have both the TM and CCC disks encrypted.

 

[casperes1996]

So I could take a TM backup and restore it to a new HDD and it would in essence create a bootable clone? Or am I not understanding you correctly?

Yes, you can do that. Get the new drive, open recovery mode on your Mac (from network recovery since I assume this is in the case of drive failure - or from a USB flash drive or whatnot) and click "reinstall from Time Machine Backup" and it'll essentially clone over the drive as it should be.

Do other people really see value in being able to restore your Mac to 3 days ago?

Well not exactly 3 days necessarily, but yes. I do.

If I make something, delete it and then realise 4 months later that I shouldn't have deleted it and I need it again, I pop open Time Machine retrieve the file and BAM I'm back in action. When I'm in the middle of something I save like you do, but when I'm done, I delete the older copies... But then you realise that you need something from an old copy or whatever, and Time Machine has your back. And all the data is accessible regardless, so if I just want to get all my music or whatever, I can also just take my entire Music folder from the Time Machine and do whatever I want with it. When I reformatted my Mac that's actually exactly what I did. I reformatted the internal SSD and I knew I didn't want all the data from my last TM backup moved over, but I wanted my Music and Movies folders, so I copied those over from the TM drive, and all the latest from those folders came over. Could also have gone back in time and retrieved an earlier version, but I just took the latest.
I personally find Time Machine really awesome, although it has glitched out on me more than once and required me to fix it with the Terminal. Fine for me, but perhaps not so great for the average Joe. Though it has been a lot more stable for me since El Cap for some reason. Not necessarily related though. Had no issues from El Cap and up
[doublepost=1513703929][/doublepost]@Weaselboy
Sorry, I stole the questions that were for you as you posted!

 

[Ambrosia7177]

Yes... if your internal drive died, you could install a new drive, then option key boot to the TM disk, then format the drive and click restore.... and you would be right back where you left off.

When you "option key boot", does that take you into Recovery Mode?

How and where are you formatting the new drive?

(If your original drive died, then I guess you couldn't "command+R boot", right?)

I'm not entirely following you, since I have never used TM or done a recovery, but it sounds like you are saying that wherever the "option key boot" would take you, that you would then use some utility to format your new, blank drive, and after doing that, you would install whichever TM backup you wanted, and then when you were done, your new drive would in essence have a working "clone" of some snapshot in time, right?

While you are doing that, would you have a working computer with your TM backup, or is this more like an old-fashioned restore off of say a backup tape?

I have a disk connected full time that does hourly TM backups.

Since the TM backups are supposedly "incremental", I guess you could have a "backup" for every day back for a couple of months and it really wouldn't take up much extra space? (As opposed to 60-days worth of CCC clones would take 60 hard-drives!)

Then every few days or so, I attach a second disk and update a CCC clone. Then I also use the app Arq to backup my users folder online to BackBlaze B2 servers in case the house burns down with my disks in it.

I'm pretty nervous about backing up my sensitive data online, but I see the point if your house burns down!

I have both the TM and CCC disks encrypted.

Good idea!

 

[casperes1996]

(If your original drive died, then I guess you couldn't "command+R boot", right?)

Command+R would not. Command+alt+R would. It's the exact same thing except instead of reading the recovery data from your drive, it reads it off of Apple's servers.

When you "option key boot", does that take you into Recovery Mode?

Option boot takes you into a screen where you can pick which disk to boot from. I've never tried since my Time Machine disk is on the network, but I assume that if you boot from the TM drive it's got some utility screen to restore its data to another disk, but not to boot directly - that's an assumption. If I restore from TM it's through the recovery screen.

Since the TM backups are supposedly "incremental", I guess you could have a "backup" for every day back for a couple of months and it really wouldn't take up much extra space? (As opposed to 60-days worth of CCC clones would take 60 hard-drives!)

Correct. I backup both my 1TB iMac as well as my 256GB MacBook Pro to a 2TB Time Capsule, and I've got about 8 months backed up or so.

While you are doing that, would you have a working computer with your TM backup, or is this more like an old-fashioned restore off of say a backup tape?

There are probably other ways of doing it, but the way I've always done this, is that I format the drive in Disk Utility (through recovery mode if necessary, either through a USB or internet recovery as options if internal disk is dead), then I install macOS on it as a fresh copy and then copy over data from the TM. You could forgo the copy of macOS and just take the one that's on the TM, assuming you haven't excluded the OS from your backup like I do, since I never need the OS itself on the backup. Have a bunch of installers lying around. It's not like if it were cloned but in the end it almost works out as well.

 

[Weaselboy]

When you "option key boot", does that take you into Recovery Mode?

How and where are you formatting the new drive?

(If your original drive died, then I guess you couldn't "command+R boot", right?)

I'm not entirely following you, since I have never used TM or done a recovery, but it sounds like you are saying that wherever the "option key boot" would take you, that you would then use some utility to format your new, blank drive, and after doing that, you would install whichever TM backup you wanted, and then when you were done, your new drive would in essence have a working "clone" of some snapshot in time, right?

While you are doing that, would you have a working computer with your TM backup, or is this more like an old-fashioned restore off of say a backup tape?!

Time Machine puts a copy of the recovery partition on the drive, so for a locally attached (like USB) drive you option key boot then pick the TM disk and that boots you to the recovery screen on the TM disk. From there you have Disk Utility to format the new drive... and there is also a restore tool.

Just for anybody else who runs across this, that feature was broken in El Capitan and is back now in Sierra and High Sierra.

When you option key boot to the TM drive, all you see is the recovery panel, and you cannot actually otherwise use the computer.

Since the TM backups are supposedly "incremental", I guess you could have a "backup" for every day back for a couple of months and it really wouldn't take up much extra space? (As opposed to 60-days worth of CCC clones would take 60 hard-drives!)

Exactly, unless you are dong something like editing huge video files that take a lot of room, a TM disk can hold a lot of old versions.

I'm pretty nervous about backing up my sensitive data online, but I see the point if your house burns down!

Arq encrypts the data before it leaves your machine, so it is perfectly safe.

 

[Ambrosia7177]

Correct. I backup both my 1TB iMac as well as my 256GB MacBook Pro to a 2TB Time Capsule, and I've got about 8 months backed up or so.

Okay.

There are probably other ways of doing it, but the way I've always done this, is that I format the drive in Disk Utility (through recovery mode if necessary, either through a USB or internet recovery as options if internal disk is dead), then I install macOS on it as a fresh copy and then copy over data from the TM. You could forgo the copy of macOS and just take the one that's on the TM, assuming you haven't excluded the OS from your backup like I do, since I never need the OS itself on the backup. Have a bunch of installers lying around. It's not like if it were cloned but in the end it almost works out as well.

So you can pick and choose what you want to backup with TM, huh? I guess you could in essence clone your existing drive, or you could just choose your personal files like it sounds like you do, or some other combination, right?

By the way, what is a "sparse bundle"?

 

[casperes1996]

So you can pick and choose what you want to backup with TM, huh? I guess you could in essence clone your existing drive, or you could just choose your personal files like it sounds like you do, or some other combination, right?

I hesitate to use the word "clone", but yes, you could tell TM to backup all data on the drive, as well as pick the Home folder only or anything else - as specific or wholistic as you want.

By the way, what is a "sparse bundle"?

A sparsebundle is a special kind of disk image that grows and shrinks on demand. Usually when you make a disk image you specify its size as it is made, but with a sparsebundle it automatically grows and shrinks to be only as large as it needs to be. Like a singular container that TM then just throws all its backups (from a single machine, each machine gets its own sparsebundle) into (with folder structures inside the sparsebundle) and then as more files are added to the backup, the bundle grows. And if there is no more space on the drive, the sparsebundle can go in and delete the oldest copies of its files and shrink the bundle again to make room for a new backup.

 

[Ambrosia7177]

I hesitate to use the word "clone", but yes, you could tell TM to backup all data on the drive, as well as pick the Home folder only or anything else - as specific or wholistic as you want.

Let me try again...

You can use TM to copy your entire hard-drive, including all system files, metadata, etc. and then save it as a TM "sparse bundle". So in a sense it is like a "clone" in that it can be used to re-create your Mac, however it it is not stored/organized in a logical manner like a "clone", so that is what makes it like any other TM backup.

When you go to restore this TM backup of your entire computer, then TM assembles the various components in the backup and when it is done all of the system files, metadata, and you data are assembled in such a way that it is like a "clone" and thus like your original real-live Mac that you backed up whenever.

Is that a more accurate description of how things work?

 

[chscag]

Just some added info: A Time Machine backup can actually be used to boot from. It will boot and does what Apple refers to as an EFI boot. So if you should be without a cloned backup (CCC or SuperDuper), you can restore and boot from a Time Machine backup.

 

[casperes1996]

Let me try again...

You can use TM to copy your entire hard-drive, including all system files, metadata, etc. and then save it as a TM "sparse bundle". So in a sense it is like a "clone" in that it can be used to re-create your Mac, however it it is not stored/organized in a logical manner like a "clone", so that is what makes it like any other TM backup.

When you go to restore this TM backup of your entire computer, then TM assembles the various components in the backup and when it is done all of the system files, metadata, and you data are assembled in such a way that it is like a "clone" and thus like your original real-live Mac that you backed up whenever.

Is that a more accurate description of how things work?

Bingo!
[doublepost=1513740965][/doublepost]

Just some added info: A Time Machine backup can actually be used to boot from. It will boot and does what Apple refers to as an EFI boot. So if you should be without a cloned backup (CCC or SuperDuper), you can restore and boot from a Time Machine backup.

I assume you refer to what Wheaselboy wrote, I.e. booting from the TM backup's recovery partition

 

[Ambrosia7177]

Bingo!

[doublepost=1513743311][/doublepost]I have some questions about Time Machine...

1.) Is there a difference between what you call a "versioned backup" and what I call an "incremental backup"?

2.) This is my understanding of how an "incremental backup" works... If you did a full backup on Monday, and then changed files and did an incremental backup on Tuesday it would save just the changes. Then if you changed the same files some more and did another incremental backup on Wednesday, it save those changes.

However, if you made more changes on Thursday, and then decided that you needed to restore thngs back to Wednesday, in order for the restore to work, it would have to piece together the full backup, plus the incremental backups on Tuesday and Wednesday.

Is that how Time Machine works?

 

[chscag]

Bingo!
[doublepost=1513740965][/doublepost]
I assume you refer to what Wheaselboy wrote, I.e. booting from the TM backup's recovery partition

Yes. The EFI boot will use information from the Recovery Partition, however, during the boot process you will not see the Recovery partition as you would if you ran First Aid using Disk Utility.

 

[Weaselboy]

You can use TM to copy your entire hard-drive, including all system files, metadata, etc. and then save it as a TM "sparse bundle".

Just to clarify on the sparse bundle point a bit. If you use TM to backup to a directly attached drive, like USB, there is no sparse bundle created or used. The entire TM backup is placed inside a Backups.backupdb file.

Now when you use TM backup to a networked drive like a Time Capsule or a NAS, a sparse bundle is created and the Backups.backupdb file is placed inside that image. What that sparse bundle image does is create a Mac compatible HFS+ image on the networked drive so the TM backup that requires HFS+ can function. This sparse bundle image can be on a NTFS or even FAT formatted drive since the image makes its own HFS+ format internally.

Because of the way sparse bundle images store data in "bands" you can even use one to get around the old DOS FAT file size limit of 4GB. Say you have an 8GB video you want to move to a FAT formatted USB key. You can put the video inside a sparse bundle and copy it to the USB key and it will work and get around the 4GB file size limit.

 

[casperes1996]

Because of the way sparse bundle images store data in "bands" you can even use one to get around the old DOS FAT file size limit of 4GB. Say you have an 8GB video you want to move to a FAT formatted USB key. You can put the video inside a sparse bundle and copy it to the USB key and it will work and get around the 4GB file size limit.

Did not know that part. Thanks for the extra info

 

[casperes1996]

1.) Is there a difference between what you call a "versioned backup" and what I call an "incremental backup"?

2.) This is my understanding of how an "incremental backup" works... If you did a full backup on Monday, and then changed files and did an incremental backup on Tuesday it would save just the changes. Then if you changed the same files some more and did another incremental backup on Wednesday, it save those changes.

Yes with a little *. I believe, though I may be mistaken, that when you make your changes, TM saves a full copy of the file that was changed again, but only the changed file and not all the files that stayed the same. – This means that it's not quite just saving the delta, since let's say you have a txt document that just says "Hey there", and you then change it to "Hey there, brown cow!", it'll keep a copy of both "Hey there" and "Hey there, brown cow!" not just "Hey there" + ", brown cow!". Did that make sense? I think this will change when TM goes APFS (which it might already work under if you format the TM drive that way - I haven't tested that).

it would have to piece together the full backup, plus the incremental backups on Tuesday and Wednesday.

Yes - In the TM backup folder each backup is denoted by its date and includes all the data that was backed up on that day, as well as links to the files that were still on the system at that point, but said links just point back to older backups (from when those files where added).

 

[Ambrosia7177]

Yes with a little *. I believe, though I may be mistaken, that when you make your changes, TM saves a full copy of the file that was changed again, but only the changed file and not all the files that stayed the same. – This means that it's not quite just saving the delta, since let's say you have a txt document that just says "Hey there", and you then change it to "Hey there, brown cow!", it'll keep a copy of both "Hey there" and "Hey there, brown cow!" not just "Hey there" + ", brown cow!". Did that make sense? I think this will change when TM goes APFS (which it might already work under if you format the TM drive that way - I haven't tested that).

Yes, I suspected that is how things worked.

Yes - In the TM backup folder each backup is denoted by its date and includes all the data that was backed up on that day, as well as links to the files that were still on the system at that point, but said links just point back to older backups (from when those files where added).

So could you argue that Time Machine is riskier because if any of the intermediary files from incremental backups became corrupt, then it would break your ability to do a full recovery?

Or, for the reasons you mentioned above, maybe Time Machine really isn't that much more suceptable to "breaking" than say a "clone". Thoughts?

 

[casperes1996]

So could you argue that Time Machine is riskier because if any of the intermediary files from incremental backups became corrupt, then it would break your ability to do a full recovery?

You could say that, yes. But in my experience at least, there's very little risk of losing such data, and total drive loss is much more likely. – If you do lose a file in one of the incremental backups however, you'll still be able to restore everything else, and it won't give you a full error, just say "This one file was corrupt", but carry on copying over the rest.

I don't personally think TM is a more error-prone backup method than any other method (assuming said method is not extremely bullet proof, like a billion different backups scattered across the Milky Way, so even if the Earth blows up, you still have a safeguard.... A bit excessive perhaps).

Your biggest potential issue with TM (That I haven't seen in a few years, but that happened to me like 5 times a year 3-4 years back), is that the backup database locks up. I.e. if my iMac is doing a backup, the Tima Machine drive doesn't realise it when it's done, so the next time you go to try and backup something or restore, your Mac complains that a backup is in progress - It was relatively easy to fix, but a bit of a hassle - though as I've said, it's been flawless for a long time now

 

[Ambrosia7177]

You could say that, yes. But in my experience at least, there's very little risk of losing such data, and total drive loss is much more likely. – If you do lose a file in one of the incremental backups however, you'll still be able to restore everything else, and it won't give you a full error, just say "This one file was corrupt", but carry on copying over the rest.

If my TM full-backup had "document.doc" (v01) and then I did a series of incremental backups (i.e. just letting TM do its thing), and lets say I was up to "document.doc" (v07) and I needed to restore things back to "document.doc" (v06), but "document.doc" (v04) was corrupt, in Time Machine, would I be able to go back to "document.doc" (v03) which was still good, or would the whole family of "document.doc" (v01-v07) become toast?

If you were using change/configuration management software (e.g. svg) you might be screwed. But I would think that "document.doc" (v01, v02, v03) would definitely be good, and maybe even "document.doc" (v05, v06, v07).

 

[monokakata]

Texas_Toast, I've been following this with interest (my backup days began with a tape drive that did a nightly incremental backup).

I think it would be helpful if you said what your goals are. I mean, for example, from what sort of difficulty or difficulties would you like to recover? And how quickly do you need to recover? I mean in general.

For example, I want to:

-- go back days, weeks, or months and find files or apps or emails that I've deleted (TM is just fine for this)
-- keep working immediately after a fatal system fault (=hosed Mac) as quickly as possible and/or being able to grab another Mac that doesn't even belong to me and boot into my own environment immediately (SuperDuper! clone on an external, made every few days, takes care of this (CCC would do the same job))
-- recover from some disaster in my work area such as a localized fire or earthquake (SuperDuper! clones of my external data drives, made every few days and stored in a fire safe in another part of the house will do that)
-- recover from a situation in which much or all of my computing operation is lost to fire or the equivalent (Backblaze and Dropbox take care of the really critical stuff)

You mentioned fire yourself. I had friends whose house was lost in the Coffee Park fire in N CA. They were using TM but not cloud backup, so they lost everything except what was on a secondary laptop they had time to grab. Had they been on Backblaze (or any of the equivalents) they could have recovered.

Anyway, there are many, many backup strategies. You'll have the best shot at choosing what's best for you if you can articulate exactly what you want to protect against, plus the time frame in which you need to get yourself back to normal.