Time Machine: "Oldest backups are deleted when your disk becomes full."

That's fine by me. I'm a backup paranoid after losing a WordStar
document from my Osborne I in 1982.

But it appears not to be working. TM says it can't backup because the
disk is too full. Based on the quote in the title, I expected it would
delete old backups to make room and go about its business.

What don't I know?

TIA!

 

Each backup only contains the files that changed since the previous
backup. The way this is done is that all the filenames for unchanged
files are hard links to the same file.

So when a backup is deleted, it only recovers space for the files that
have newer versions in the next backup. If most of them didn't change,
deleting the backup won't get you much space. This can easily happen if
your disk is full of archives of images and movies that you never modify
or delete -- all backups will be 90% the same stuff.

 

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On Saturday, 26 April 2014 00:59 -0400,

If you read the fine print, in the notice, it says that the deletion
will take place, the next time Time Machine runs. I have such a post
deletion backup running, at this time.

- --
David Ritz <>
Be kind to animals; kiss a shark.

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To clarify, there are two possible scenarios and I'm not sure which one
you are encountering.

(a) If you are trying to back up a new computer to a drive which is
already being used for Time Machine backups of other computers, then the
new backup can only start if there is enough free space. Time Machine
will only delete old backups from the same computer in order to free up
space for new backups.

Note that some instances of computer/drive replacement might result in
Time Machine thinking it needs to start a new backup rather than
continuing an existing one. (I encountered this once when I was running
somewhere around 10.5/10.6, but not when I had a similar situation
around the 10.8/10.9 timeframe, so Apple may have improved the logic in
later OS X versions.)

(b) If nothing out of the ordinary has happened and TM has just reached
the point where the backup disk is full, then it should be able to work
as advertised, by deleting the oldest backup (or several old backups) of
this computer to make room for the next backup.

If there has been a significant change on the computer, such as adding a
new large drive or lots of files on an existing drive that need to be
added to the backup (including moving or renaming a huge folder) this
can trigger a situation where TM thinks it can't delete enough old
backups to make room - it needs to be able to retain at least one old
backup.

 

In this case it may be possible to use the shell command:
inheritbackup {machine_directory | sparsebundle} ot accquire the old backup.

I used this technique to "inherit" a backup sparsebundle produced on an
old MacBook by its replacement.

 

easily done using the command line utility tmutil in lion and later.

it's possible to do it in earlier systems but it's a pain in the ass.

 

Davoud:
David Empson:

Not the case.

Not the case.

That's the case, as far as I know.

That's my thinking. Simple enough, so I thought. I didn't understand
Mr. Margolin's explanation at all. It has been working all along.

Not the case.

TM just quit working one day. April 24, to be specific.

I think that I'll erase the TM volume and turn it into a SuperDuper
backup volume. I've already got one of those for this machine; one more
can't hurt.

Thanks for taking time to reply.

 

What exactly does it say? Sometimes when the big print says the disk is
full, the fine print says it isn't because Time Machine deleted some old
files.