time machine concerns

[homeshire]

Having bought and installed Leopard, I did what any right-thinking individual would do. I went out and bought my first external HD and fired up time machine. Everything went smoothly for a good couple months.

Then one day I started noticing that even though I had not generated much since my previous backup, my sessions with time machine were getting larger and larger. First, a few hundred megs, finally 1.8 gigs, even though I hadn't done much.

At that point, I wiped the drive and started all over again, just out of anger and frustration. But I have found that even though I am not doing very much, my backups started out again as hundreds of megs. I have a suspicion that it is just a huge empty block.

but I don't know why, or how to stop it. Does anyone have an explanation or a solution to how I can stop this?? I hate chewing up hundreds of megs for nothing. The drive will be full way before it should be with this madness.

thanks for any help.

 

[hodgjy]

It all depends on what applications you are using and what kind of files you are making.

Time Machine is smart in that it backs up only the files that have been changed. However, it's dumb because, due to the current HFS+ filing system, it updates the entire file instead of only parts of the file. For example, if you're running Parallels to use Windows, that's a several gigabyte file on your computer. Every time you use Parallels, the file changes. Thus, Time Machine backs up that several gigabyte file over and over and over.

The same is with any file. If you change documents, preference files, pictures, etc, etc....Time Machine will back them all up over and over. So, even if your changes in the file are small, say 1 bit in a 1 megabyte file, Time Machine will backup the entire 1 megabyte file again and again rather than only updating the one bit change.

This is more a limitation of the HFS+ file system instead of Time Machine itself. You can exclude Time Machine from backing up certain files just for this reason. I have Time Machine ignoring my Parallels folder because it was making 1.6 gigabyte backups several times a day.

 

[tyr2]

If you're prepared to use the terminal you could use a script I wrote a while ago that will compare two backups and tell you what's using the space.

One day I'll get around to writing a nice interface for it.

 

[Virgil-TB2]

It all depends on what applications you are using and what kind of files you are making....

I would look at what you are excluding from the backup also.

Short list of things you should specifically *exclude*:

- any folders where you download bit-torrents or limewire or any of those kinds of things
- Entourage database (better yet just don't use Entourage at all)
- any folders you use for processing videos etc.
- any large media stores that change a lot.

Entourage alone can fill up a Time Machine drive in no time as the database can be a Gig or two and changes every single day.

 

[homeshire]

you've all made some good and pointed suggestions. the problem is i do not see a single thing among them that i would be guilty of. all things that you say i should exclude have been excluded. i don't use entourage.

I did in fact do a little work i iMovie for my daughter's high school homework about the time of all this, but i have since discovered those files and deleted them. so if they were an issue, they should have been gone.

i am on a g5, so parallels, et al. are a non-issue on this machine.

as i have said, i have gone just less than 24 hrs. between backups, and for 21 or so of those hours the machine was powered down. while up for maybe a couple hours, i did the classic surfing and email, nothing else. no heavy video or imaging. nothing heavy duty. and still getting huge blocks of backup.

i just can't figure out what it is doing.

thanks

 

[bacaramac]

There are several threads on how TM works. Basically if you delete those files, as of the last back-up before you deleted the movie you can still find it. That is how TM works. If I deleted a movie 6 months ago and I had the space, I could go back six months in TM and bring that file back to life. So by deleting you are only deleting it from your current files, not TM's backed up files.

As for the 24hr thing, I am not sure. Anything I want backed up I have on External drives, so my Mac Mini HD is completely left out of TM back ups. All the surfing, iMovie stuff does not play into TM Back-ups.