[MacNNUK]

I know it's not doing a full backup because of the short time each "incremental backup" takes, yet in Finder, each back-up shows as a full 175gb backup, and so apparently limits backups to a couple of days on my 500gb Time Machine, as each backup reportedly uses around 175gb !

Even those that take only a few seconds to perform.

This has happened since I reinstalled 10.7.3 two days ago, from Time Machine, using Recovery !!


Update, when I add up all the 167-175gbs, it adds up to 3,600gb on my 500gb Time Machine HDD !!, so not a true reading then

Something else must have happened once I had restored 10.7.3 from Time Machine, I did note the first backup after restoring was a full 175gb backup, took 3 hours, and involved lots of deletions of older backups, but 300gbs worth ?

Here's a clue, the actual backups must not actually use up 175gb of data on the HDD, but cleansing removed my many older smaller backups, prior to first backup after restoring, problem solved, I think...



I've got into the habit of screen grabbing active windows as software is updated , assigned f2 key to do this, in keyboard shortcuts prefs.

Still showing 167gb backups after UpdCombo10.7.3

[ibook_steve]

I'm sure somebody else can explain it better, but from what I understand about TM, even though there are multiple backups on the drive, any file that has not changed between backups does not contribute to any additional storage space. So even though you see multiple 160+ GB backups, there's really only one base backup with incremental changes added on. Think about it. If they really were that big, your 500 GB drive would be full after only 3 backups (160 x 3 = 480 GB; I think you're getting your GB mixed up with your TB (terabytes) in your post).

I'm not sure why your backups reset and you lost all the old ones. You mention restoring from TM. If that was a full system restore, then TM would start over with a brand new backup of the entire drive.

Steve

[MacNNUK]

I concur with what you say, I had in fact just updated in Red my latest thoughts after checking back through all my old screen grabs since new iMac 10.7 arrived.

TB GB amended.

Thanks.

Originally Posted by ibook_steve 

I'm not sure why your backups reset and you lost all the old ones. You mention restoring from TM. If that was a full system restore, then TM would start over with a brand new backup of the entire drive.

Steve

This explains a lot, and the deletion of older backups to make 125gb+ room on the backup drive, thanks.

I seem to remember reading somewhere that backups require up to twice the disc space to back up.

Hence the figures of 125gb required, 239gb made available



I'm a bit miffed at losing previous backups though, as I had purposely done a backup of the virgin 10.7.3 installation on my new iMac, just in case.

And many backups as I add or amended items, to easily revert back if a problem arises.

And if Time Machine thinks the latest backup is the only one to keep, what about all those files and folders moved or deleted in the past ?

I do regularly manually copy most folders to a 1tb external HDD as another backup, thankfully.
As was needed when I couldn't access previous Time Machine backups from my previous iMac !

[mduell]

Time Machine uses hard links for deduplication on the backup drive, so the same file appearing in multiple directories (i.e. different backup times) reference the same blocks on disks. But the size of each directory still appears to be the total size of it's contents.

Some more advanced file systems even support this at the block level, so if you make 1 MB of changes in a 500MB file, the total storage consumed by the old version and the new version only occupies 501MB of disk space.

[CharlesS]

TimeTracker can show you what Time Machine's really doing:

http://www.charlessoft.com/TimeTracker.zip

[MacNNUK]

Originally Posted by CharlesS 

TimeTracker can show you what Time Machine's really doing:

http://www.charlessoft.com/TimeTracker.zip

Interesting app, thanks