MacBook Pro back up to external hard drive

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MacBook Pro back up to external hard drive

The last 2 times I have backed up my MacBook Pro to my WD Passport external hard drive, it has only backed up 23 and 30 GB, even though I have used 219 GB on my MacBook Pro. I have plenty of space on the external drive.....1 TB.

Is it only backing up things that have changed since the previous backup? How do I tell if my entire hard drive is truly backed up, or if it is only selecting certain things to back up? I am considering purchasing a new computer and using the current one for mainly photos and misc. files, so I want to be certain everything is properly saved so I'll be able to transfer them if/when I buy a new MacBook.

Mac Pro

Posted on Sep 27, 2019 12:46 AM

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Answer 1

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dwb

Level 7

32,962 points

Sep 27, 2019 6:30 AM in response to Debru4

You didn't tell us how you are backing up your computer so I'm going to assume you are using TimeMachine and paying attention to what TimeMachine reports after each backup session.

The first time you connect the external drive to your computer and start a TimeMachine backup, TimeMachine backs up the contents of the entire drive. After that initial backup TM backs up only what has changed since the previous backup. Sitting at my desktop where TM backs up every hour, my last backup was less that 50 MB since little changed over the previous hour. This is how TM works.

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Answer 2

Sep 27, 2019 8:40 AM in response to Debru4

Time machine keeps a complex database of what files are already included in previous dated backups. Everything it has backed up is tracked together as a backup "set".

This means that:

Once the initial full backup is in place, it can be used as the basis for incremental backups.

incremental backups (hourly by default) are small, and completion of the backup is fairly quick

you are not to manually (using Finder) delete things out of a backup set, or you risk damaging the database.

Time machine manages the remaining space available on the backup drive by removing oldest and redundant dated backups; this is a consolidation rather than a deletion, so it takes time.

Time machine's coolest trick:

Time machine can restore the LAST state of your Mac and ALL its files; But it can also restore the state as of ANY dated backup it still holds, or can restore a single file or a group of files as of that date.

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Answer 3

Debru4 Author

Level 1

15 points

Sep 27, 2019 12:31 PM in response to dwb

Although I have used Apple/Mac computers since the early 80's (Yup, still have my original Apple2e😉), most of those years were when I was teaching, and I had a school technologist who helped me with back ups/answering questions. I am now retired, and realized that I don't understand the processes very well, so I have lots of learning to do. My external hard drive is not always plugged in as I move my MacBook around a lot. When I get a reminder to back up, I try to do it then. Another thing that confuses me is that when I plug the drive into my computer, at first it appears green, with one name, and then changes to yellow with another. Sometimes I get a message that I have not backed it up in over 600 days. Other times, that it's been 30 days. I am assuming it has been partitioned somehow? (I didn't knowingly do it.) I do have Time Machine on my computer----is there a way to back up to the external drive without using Time Machine? Whatever I do, I want to have a full backup available should my computer fail or I buy a new one, as I have 230 GB of things on it that are important to me. I appreciate your taking the time to respond. Thank you!

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Answer 4

Debru4 Author

Level 1

15 points

Sep 27, 2019 12:34 PM in response to Grant Bennet-Alder

"Time machine's coolest trick:

Time machine can restore the LAST state of your Mac and ALL its files; But it can also restore the state as of ANY dated backup it still holds, or can restore a single file or a group of files as of that date."

Grant---are there directions on how I would actually be able to retrieve this? I am assuming you are describing what Time Machine is designed to do, and not something special I need to do to enable this function?

Although I have used Apple/Mac computers since the early 80's (Yup, still have my original Apple2e😉), most of those years were when I was teaching, and I had a school technologist who helped me with back ups/answering questions. I am now retired, and realized that I don't understand the processes very well, so I have lots of learning to do. My external hard drive is not always plugged in as I move my MacBook around a lot. When I get a reminder to back up, I try to do it then.

Another thing that confuses me is that when I plug the drive into my computer, at first it appears green, with one name, and then changes to yellow with another. Sometimes I get a message that I have not backed it up in over 600 days. Other times, that it's been 30 days. I am assuming it has been partitioned somehow? (I didn't knowingly do it.) I do have Time Machine on my computer----is there a way to back up to the external drive without using Time Machine? Whatever I do, I want to have a full backup available should my computer fail or I buy a new one, as I have 230 GB of things on it that are important to me. I appreciate your taking the time to respond. Thank you!

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Answer 5

Sep 27, 2019 12:43 PM in response to Debru4

Time Machine depends on a MacOS data structure called the File System Event Store, which is of finite size, so it can only track the most recent few days of changed folders. If you connect your drive every few days, the Event store is still applicable, and you backup can proceed immediately.

If you put off connecting the drive for a week or more, the Event Store is likely stale, and then Time machine needs to do a "deep traversal" of both your files and your backups to figure out what has changed. This can take four hours before any files are tranferred.

Time machine is designed to work at low priority in the background, so that you can continue to do your work. There is no need (and no advantage) to set aside special time to do backups. Time machine backups are the backups most likely to "be there" when you need them, because you do not have to put them off for a time when you can focus on doing backups.

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MacBook Pro back up to external hard drive

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