Q: What is the best solution when my Time Machine external drive becomes full?

older files start to get deleted as the drive fills up so yes, they're gone

the backup drive should ideally be 4x the capacity of your current drive, twice is good but has limitations. Also factor what are you storing: A jpeg from the web and a raw photo file are both images, the size of either is vastly different. If you work in High-Res or large native files, or audio files (pro recording, not music files) or video production twice the drive will fill up very fast. if you collect pics and jpegs and mp3's or a handful of videos not as much is needed.

I would keep the old drive intact if you are going to replace it and start fresh with a new drive if thats the plan. You have the old data, you can keep it in a safe place and have a redundant backup that you can reconnect at any time to restore from. Let the new drive index itself with new data and take if from there, otherwise you can copy the backup to the new drive and set the drive as the new backup source but personally I'd avoid copying the data, it's my preference, it may not be yours and thats fine.

No. If you want to copy the old backup to the new drive, get an external drive with no data on it. Try booting into the Recovery Partition (command - R on a restart) and select the drive in Disk Utility, then Edit/Restore and select your internal drive in Restore from. This will likely reformat the external drive erasing all data.

When it deletes old backups, it is not deleting the last backup of a file if the file still exists on the Mac it is backing up. What you will lose is older versions of a file that may have been backed up.

The answers to a lot of your Time Machine questions can be found here: http://pondini.org

It is a little dated because the author passed away some years ago.

My advice is to buy a drive that is at least 3 times the size of the data you wish to back up and start over.

Time Machine is not an Archival Backup in that if you delete something from your hard drive, Time Machine will eventually delete it from the Backup. So, if you think you are preserving anything but older versions of documents by re-using the old TM backup, you are potentially going to be disappointed that files you deleted from your hard drive no longer exist.

You cannot "span" disks in time machine. You could create a Fusion drive out of two disks, but I'm not sure if you can do that and keep the data from the original drive.

Although I am backing up to a Fusion drive currently, I'm still a little wary about its viability--my photos and Movies are backed up separately.

Hi,

I've known and used Time Machine for a long time.

In short, what I would do if I were you is that I would continue using the current external hard drive for backups. As long as the external hard drive is approximately as big as the current internal disk usage, you'll be safe. At the same time, I would buy a second, bigger drive, and set it up as Time Machine target. (I am in the exact same situation as you. I have an external 2GB  2,5" pocket drive and a 4GB Time Capsule)

It is always better to have two backups than one only. Read further for details of different options/strategy...

In long, here is how Time Machine works. And it works well, I'm using it for years to backup and restore (full systems). There have been some glitsches in the past, but not recently.

What time Machine does really when you have 2 or more target drives is that every hour, it will backup to the next drive. So if you have only one Time Machine external backup drive, you'll get a backup every hour. If you have 3 ext drives, you'll have a backup every 3 hours on each drive.

To answer your questions, what Time machine does when the ext drive reaches the capacity limit is:

- Time Machine tries to delete old backups until there is enough space for new backups. Each backup you can see it as a complete image of your disk at the time of the backup, only it doesn't use the same space on the ext drive  as your internal disk, because copies are "incremental". Each new backup records only the differences from the previous backup.

- Time Machine always insures that you have at least one FULL backup on the ext drive. If the total capacity of your ext your drive is smaller than approx. usage of your internal drive, then Time Machine will fail, and you'll be informed.

- something you might not see clearly (not sure if I understood you well on this). Time Machine will not delete files from the backups that aren't deleted on your main drive. See ? Let's say you've got 50,000 photos in your Photos App. One day you decide to delete 10,000. Time machine will keep 50,000 photos. Until the ext drive is full. Then Time Machine will also delete the pictures that you deleted from your Photos App. But Time Machine will never delete Photos from backups that you didn't already delete yourself in your App. The reason why it is better to have at least a few days, weeks, months of history in Time Machine (you need space for that) is that in case you accidentally deleted the 10,000 images from the Photo App, you can then find them back in last weeks backups...

- The more history you need, the bigger ext. drive you need.

The strategy I followed was the following.

When my 2GB ext hard drive was reaching capacity limit, Time Machine started to delete old backups. I wanted to keep the longest possible history.... you never know.

So I simply bought a 4 GB ext hard drive (or Time Capsule, to be specifi, but doesn't matter).

Then I cloned the 2GB drive on top of the 4GB drive. Therefore my new 4GB hard drive inherited the whole Time Machine history from the 2GB drive.

So what I have now is that:

- the 2GB hard drive is full but still can hold a few days history of Time Machine backups. I keep that disk in case of a complete crash, system disk failure, a theft/robbery, you name it. I keep that disk away, like in the garage, or in the car (it's encrypted), in the suitcase when I go away. This disk is updated every now and then, just to be able to restore my system in case I lose everything.

- the 4GB Time Capsule is used by Time Machine to make an incremental backup every hour, and I use this disk in case I eleted a file by mistake. Last week, a system crash (hardware failure) destryed my Final Cut Pro X database. In no time, I had time Machine restore the lastest DB.

- when I start Time Machine software on my Mac, I see a consistent collection of backup dates, no matter on which disk the data actually is.

Another alternative you could do:

- keep your current ext backup drive as is, stop using it as Time Machine target. You must do that otherwise Time Machine will continue deleting old backups whenever you plug the drive in your Mac.

- start fresh on a new , bigger, hard drive.

In that case, you'll have backups and all history prior to today archived on your "old" backup drive, and all new and future backups will be found on the new hard drive.

The drawback I think is that if you disable your "old" ext drive as Time Machine target (and you must do so), you'll probably not be able to use Time Machine to restore from that drive. But you can still browse the files with Finder.

Just to finish up: Time Machine rocks. Thank you Apple for making this !

I work on PC and Linux and have experimented many personal software solutions, and nothing really reaches the stability, quality and simplicity of Apple Time Machine.

Besides, please note that Apple Time Machine will soon support SMB drives, meaning you'll be able to officially use third-party NAS (synology, etc...) or Windows Servers as Time Machine targets.

Let me know if you need more info.

Jimmy,

Just to avoid any misunderstanding.

The way Time Machine work is that it will indeed "delete" any file you actually delete on your hard-drive, but those changes will *only* be reflected in future backups.

Say you have a backup running every hour sharp.

The files you just deleted from your Photos App at 10.10am will still show up in Time Machine backups prior to this time. That means that the pictures you just lost still show up in the Time Machine backup of, let's say 10.00am, and in every other older backup too.

The backup type is incremental and thanks to the genius usage of file system hard links (well, at first they used standard hard-links and they they modified the OS filesystem to support multi-links), you can delete virtually any backup without compromising the integrity of the whole backup set, not to mention you don't need a specific "full initial backup" like other incremental solution require... any backup you delete, it's the oldest backup which automatically becomes the "initial full backup", without any software needed to do it; it's like hard-wired in the filesystem code :-)

Genius :-)

And Time Machine will certainly be improved a lot with the upcoming hot new feature coming soon to MacOS: APFS.

Cheers.

Brian,

You have to keep in mind that no matter how many versions of a file shows in backup history, this file will actually be stored only once on the storage, because Time  Machine uses multi-links. Unless your file has changed in the meantime, of course.

In your example, the RAW images will show in every version of the Time Machine backups since day 1, but those will occupy only once the space on the disk. Time Machine will only show you references of those files.

And no, Time Machine will never delete those files as long as you don't delete them from your internal hard drive.

Otherwise, if you deleted the files from your main hard drive, Time Machine will also keep the files in backups, until your backup drive runs out of disk space. What will happen there is very simple. Time Machine will simply delete old backups (it doesn't delete individual files, but complete backups, because each backup must always be FULL) starting with the oldest.

So, when your ext disk runs out of space, as long as the oldest backup that Time Machine decides to keep actually contains those files (that you deleted later), you're safe. they are there.

To summarize, I'd say as soon as you see "deleting old backups" (you can have the system warn you before it actually does that), you should increase your disk, provided you want to keep history.

Also, do no mix-up notions of backups or archive.

Eric,

Not sure what you mean.

Brian isn't trying to clone his system disk. He's just asking questions regarding external backup disks and Time Machine...