Why isn't it just deleting the oldest backups when it needs more space?
I had to manually delete old backups from the drive.
Clearly the following is a blatant lie! :)
iMac 21.5″, macOS 10.13
And then I'll be back here in couple of years when the issue recurs. :)
And, it likely will if the backup disk is full.
Yes, Time Machine is supposed to delete older backups to make room for newer backups. This usually works OK.....IF.....the new backups are small "incremental" type backups.
BUT......if the new backup is larger than normal, which could occur after new data...pictures, video, music, etc is added to the Mac, or an operating system update was just performed......THEN....Time Machine cannot delete enough of the old backups to make room for the new larger than normal backup.
Of course.....Apple does not mention details like this in their Time Machine documentation.
Bottom line.....if you want to maintain a complete history of backups......add a new backup disk when the current backup disk is close to being full.
And then I'll be back here in couple of years when the issue recurs. :)
And, it likely will if the backup disk is full.
Yes, Time Machine is supposed to delete older backups to make room for newer backups. This usually works OK.....IF.....the new backups are small "incremental" type backups.
BUT......if the new backup is larger than normal, which could occur after new data...pictures, video, music, etc is added to the Mac, or an operating system update was just performed......THEN....Time Machine cannot delete enough of the old backups to make room for the new larger than normal backup.
Of course.....Apple does not mention details like this in their Time Machine documentation.
Bottom line.....if you want to maintain a complete history of backups......add a new backup disk when the current backup disk is close to being full.
I manually deleted some old backup folders, and it's happy again.
That action will corrupt Time Machine's database. That backup should no longer be considered reliable. Erase it and start a new set.
Next time ask here first. Post or capture a screenshot of the exact failure message.
"Time Machine could not complete the backup because the disk is full" error?
The exact wording of the error message is important. A backup can fail if the source volume cannot contain sufficient "Local Snapshots" to complete a backup (for example) but that can only occur if a backup is prevented from completing while simultaneously adding a large amount of new material waiting to be backed up.
Having insufficient space on the backup volume is rare because old and "expired" backups are automatically removed as they age. The most common reason for that is when a user renames a source volume, or if the source volume becomes renamed for some other reason. TM will effectively archive and never again touch what it considers the "original" source, resulting in the potential for an enormous amount of occupied space that can no longer be used.
So you're saying that deleting some old Time Machine folders could make some files irretrievable? Is that because Time Machine always does incremental backups after the initial full backup?
Deleting TM backups corrupts TM's database. That corruption may or may not become evident until the user wants to restore an item or an entire backup.
It never does periodic full backups?
No. After the initial backup they are all incremental.
Before you erase it, consider getting at least one additional backup drive and adding it to Time Machine. Apple recommends that its capacity "... should have at least twice the storage capacity of every disk or volume you're backing up." That's an oversimplification in my opinion but it keeps complaints to a minimum.
It's not a bad idea to erase the backup drive once in a while. Even though TM will delete old and "expired" backups when it requires the space they occupy for newer ones, retaining two or three years worth (or more) of old backups is unnecessary since the likelihood of having to recover a file from months ago diminishes with the passage of time.
Besides, one and only one backup drive does not comprise a robust backup strategy. Any device can fail at any time, and it's easy to imagine a single catastrophic event resulting in the destruction of both the Mac and its backup.
Conventional USB backup drives are cheap. They don't have to be fast.
Bob Timmons wrote:
BUT......if the new backup is larger than normal, which could occur after new data...pictures, video, music, etc is added to the Mac, or an operating system update was just performed......THEN....Time Machine cannot delete enough of the old backups to make room for the new larger than normal backup.
AND... it won't do that until after that backup is complete, which means it needs to start with a lot of free space to begin with.
That way, the user is always left with an absolute minimum of one and only one complete, restorable backup — the only thing TM guarantees.
Most likely the error message was referring to the boot drive and not the external TM backup drive. How much Free space does the boot drive have? You will need to use Disk Utility....click on the "Data" volume on the left pane of Disk Utility and check the "Free" value on the right pane (it should be the right most part of the bar with the value just beneath the bar).
I'm not sure how much Free space you may need here, but you should always have at least 20GB+ of Free space available at all times for the normal operation of macOS. For some workloads you may need even more Free space.
desertcanine wrote:
No, the error was definitely from Time Machine.
I've seen some users report a space issue, but it was apparently referring to the boot drive.
I manually deleted some old backup folders, and it's happy again.
Glad that worked. Thanks for the follow up.
But, I shouldn't have to do that.
Time Machine should delete the oldest backup(s) as needed.
Agreed. I'm not sure why it didn't.
You can provide Apple with product feedback here:
No, the error was definitely from Time Machine.
I manually deleted some old backup folders, and it's happy again.
But, I shouldn't have to do that.
Time Machine should delete the oldest backup(s) as needed.
So you're saying that deleting some old Time Machine folders could make some files irretrievable? Is that because Time Machine always does incremental backups after the initial full backup? It never does periodic full backups? And if that's the case, how would I get around this "Time Machine could not complete the backup because the disk is full" error? (That's not the actual error message, but that was the gist).
Thanks for everyone's feedback!
Well then, I guess I'll wipe it clean and start over.
There's nothing I've deleted that I would need to recover.
And then I'll be back here in couple of years when the issue recurs. :)
This was the error message...
"it's easy to imagine a single catastrophic event resulting in the destruction of both the Mac and its backup"
Good point! As someone who has been managing IT operations for 30+ years, I can certainly relate to that!
Thanks again.
More than 30 years ago:
"So from then on, Paul always has a copy of his software buried in that ammo can."
Yikes! I still have a few 8" floppies with FORTRAN code back from my college days ... and yes, stored them in those ammo cans. ;) Thanks for that link. I had a good laugh.
Why is Time Machine failing to do a backup because the drive is out of disk space?
