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subjonas

macrumors 603
Original poster
Feb 10, 2014
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“Normal” meaning like a non-bootable external drive. Sorry, this may be a dumb question, but I have no experience with this and I couldn’t seem to find the answer via search. Maybe because it’s so rudimentary. Also not sure this is the right forum for this.

The background for this question is I plan to keep an external portable drive connected to my Mac that I can grab at any time on my way out the door, and I basically want it to be a 1:1 copy of all the data on my Mac, and just one-way sync. But I figured it might as well also be bootable while I’m at it, just in case the need to boot ever arises. But only if that doesn’t interfere with easily accessing its data like a normal external drive.

I was planning to buy Carbon Copy Cloner to set up the clone drive. But if the drive being a clone/bootable does interfere, does CCC have an option to one-way sync an entire computer to an external drive without making it bootable? Or do I need other software?

Also a side unrelated question about CCC if anyone knows- if I put a MacBook into target disk mode and connect it to my Mac mini, can I use CCC on my Mac mini to clone my MacBook to another drive? I need to occasionally clone my MacBook (definitely needs to be bootable in this case) and just trying to see if I can avoid buying CCC twice (for each computer).

I appreciate the help!
 
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Fishrrman

macrumors Penryn
Feb 20, 2009
29,204
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"Quick q- can you plug an external boot drive into a computer and just view/copy files normally?"

Yes.
Of course.
That's what having a "cloned backup" is all about, and why it's so convenient.
It's also why a cloned backup is SUPERIOR to any other kind, in my opinion.
 
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subjonas

macrumors 603
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Feb 10, 2014
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Oh wait, I may have just realized cloning won’t work for me. Do clones need to be made from scratch each time? I wanted a drive that will stay up to date with all file changes—immediately would be ideal, but by the hour at the longest. Something that would work in the background, only updating files that have changed, like time machine does (but 1:1 sync so not time machine).
Will CCC or another software allow me to clone once and then keep the two drives in sync going forward?
Apologies, I’m a bit confused.
 

Brian33

macrumors 65816
Apr 30, 2008
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USA (Virginia)
Also a side unrelated question about CCC if anyone knows- if I put a MacBook into target disk mode and connect it to my Mac mini, can I use CCC on my Mac mini to clone my MacBook to another drive? I need to occasionally clone my MacBook (definitely needs to be bootable in this case) and just trying to see if I can avoid buying CCC twice (for each computer).
I believe the target disk mode technique would work, and you could use the trial mode of CCC to verify that. But you don't need to -- one license is sufficient (if it's non-commercial use), according to CCC's purchase page:

Personal & Household License:
For non-commercial use on all computers in your household.

I've been super-impressed with CCC's quality, completeness, and support -- it's a fantastic software product from a reliable company. However, I also like Time Machine. (I use both.)

Do clones need to be made from scratch each time? I wanted a drive that will stay up to date with all file changes—immediately would be ideal, but by the hour at the longest. Something that would work in the background, only updating files that have changed, like time machine does (but 1:1 sync so not time machine).

You might not want to discount using TM so quickly -- it depends upon what you need. Many people don't realize that you can navigate the TM backup with Finder (or Terminal.app) just like you do on the originating Mac. Granted, you have to double-click on a few (four) more folders (Backups.backupdb and <machine name> and Latest and 'Macintosh HD') to get to the "root" directory of the boot drive, but from there on it is exactly like the file layout on the source machine. Very much like a 1:1 copy.

Regarding clones, generally they don't need to be completely re-copied every time -- only the files that have changed since the last backup are copied. CCC-type clones are typically run once a day, but you could schedule it every hour. However, IMHO running CCC every hour would not be as efficient as running Time Machine every hour. Here's why I think that: every time the scheduled CCC task runs, it scans all files on the source volume and compares the modification timestamps to the corresponding file on the backup volume. On the other hand, TM (usually) can access a journal that essentially lists what files have been updated since the last backup -- it doesn't need to go through the entire filesystem to find out which files have changed in the last hour. (NOTE: this is my understanding, and I could be wrong about this.)

Whether this makes a real-world significant difference depends on how "big" your filesystem is and the speed of the connection to the external backup volume. On my 2015 iMac, with Thunderbolt-2 connected HDD as backup target, a "null/empty" backup in CCC takes a bit over 4 minutes. On my 2011 Macbook Pro with internal SSD and a USB-connected HDD as backup target, I think it takes 10 or 15 minutes!

What I recommend is first think about whether TM will do what you want (for free). If not, try CCC's 30-day trial, and schedule a backup every hour. See it it's fast enough for you. If so, go for it!

Good luck!
 
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Fishrrman

macrumors Penryn
Feb 20, 2009
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"Do clones need to be made from scratch each time?"

No.
CarbonCopyCloner will do an "incremental update" to a cloned drive, copying only changed files to the backup (and it also deletes from the backup files you have deleted from the internal drive).

I can do an incremental backup of my "main" data partition (it's data only) using CCC, in about 5 seconds flat (my backup is on an SSD).
 
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subjonas

macrumors 603
Original poster
Feb 10, 2014
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I believe the target disk mode technique would work, and you could use the trial mode of CCC to verify that. But you don't need to -- one license is sufficient (if it's non-commercial use), according to CCC's purchase page:

I've been super-impressed with CCC's quality, completeness, and support -- it's a fantastic software product from a reliable company. However, I also like Time Machine. (I use both.)
Oh that’s outstanding they allow use with multiple computers!

You might not want to discount using TM so quickly -- it depends upon what you need. Many people don't realize that you can navigate the TM backup with Finder (or Terminal.app) just like you do on the originating Mac. Granted, you have to double-click on a few (four) more folders (Backups.backupdb and <machine name> and Latest and 'Macintosh HD') to get to the "root" directory of the boot drive, but from there on it is exactly like the file layout on the source machine. Very much like a 1:1 copy.
Oh cool, I didn’t realize that. A few double clicks isn’t bad, but I think the bigger issue is versioning and ssd’s. I don’t need versioning in this case, and though having more versions than I need isn’t itself a problem, the issue is that I’ll be using an ssd. Because Time machine versions, it will fill up the ssd quickly and keep it filled, which, as I understand it, significantly degrades an ssd’s endurance/longevity. So I believe I need syncing software for this.

Regarding clones, generally they don't need to be completely re-copied every time -- only the files that have changed since the last backup are copied. CCC-type clones are typically run once a day, but you could schedule it every hour. However, IMHO running CCC every hour would not be as efficient as running Time Machine every hour. Here's why I think that: every time the scheduled CCC task runs, it scans all files on the source volume and compares the modification timestamps to the corresponding file on the backup volume. On the other hand, TM (usually) can access a journal that essentially lists what files have been updated since the last backup -- it doesn't need to go through the entire filesystem to find out which files have changed in the last hour. (NOTE: this is my understanding, and I could be wrong about this.)

Whether this makes a real-world significant difference depends on how "big" your filesystem is and the speed of the connection to the external backup volume. On my 2015 iMac, with Thunderbolt-2 connected HDD as backup target, a "null/empty" backup in CCC takes a bit over 4 minutes. On my 2011 Macbook Pro with internal SSD and a USB-connected HDD as backup target, I think it takes 10 or 15 minutes!

What I recommend is first think about whether TM will do what you want (for free). If not, try CCC's 30-day trial, and schedule a backup every hour. See it it's fast enough for you. If so, go for it!

Good luck!
I appreciate the input! Fyi, I’m using a 2014 Mac mini with, as of now, about 2tb of data spread between its 1TB internal hdd and a 4tb external hdd (connected by usb3), and all that data (2tb and growing) will be synced to the target drive which will be a 3 or 4tb ssd connected by usb3.

My Mac mini is basically just a file and media hub, as I do all my work on other devices, then transfer my files to the mini when I’m done or at milestones, for archiving and backup to time machine. So I would ideally like a software that ran low key in the background of the mini to keep my portable drive up-to-date with all the mini’s files. Now that I think about it, a once a day schedule would probably be adequate for cloning, because since an incremental clone should only take a few minutes, I could just run the clone one more time before I grab it and head out. Now just need to decide on the ssd to buy...

"Do clones need to be made from scratch each time?"

No.
CarbonCopyCloner will do an "incremental update" to a cloned drive, copying only changed files to the backup (and it also deletes from the backup files you have deleted from the internal drive).

I can do an incremental backup of my "main" data partition (it's data only) using CCC, in about 5 seconds flat (my backup is on an SSD).
Awesome, ccc sounds like what I need then. 5 seconds, that is incredible!
 
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sgtaylor5

macrumors 6502a
Aug 6, 2017
721
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Cheney, WA, USA
Of course you’d probably have to have USB-C, or another fast port and a solid-state external hard drive to attain a 5 second time! That IS impressive.
 

theSeb

macrumors 604
Aug 10, 2010
7,466
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none
"Do clones need to be made from scratch each time?"

No.
CarbonCopyCloner will do an "incremental update" to a cloned drive, copying only changed files to the backup (and it also deletes from the backup files you have deleted from the internal drive).

I can do an incremental backup of my "main" data partition (it's data only) using CCC, in about 5 seconds flat (my backup is on an SSD).
CCC will only delete files from the target drive when a file has been deleted on the source if you have switched off safety net and are backing up a non-APFS source. APFS source backups use snapshots so you can get deleted files back. They are not simply deleted forever. Safety net is designed for similar capability on non-APFS sources.

This is actually a good thing because your deleted files were just removed forever, then CCC would not be a good backup strategy by itself
 
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