RichB

I have had loads of problems with Leopard recently and my two Lacie USB2 drives have been playing up. I have just reformatted both of them and set off Time Machine again on the 500gb.

Can anyone anyone running Time Machine confirm that your machine is showing the same results as mine:

Its a 500gb drive so theres about 460gb of space or whatever, it has done its first back up of the system and reports that as 95gb, it now backups up the changed files hourly as it should but every folder 2008-01-03-110000 for example is also reporting its size at 95gb.
If I open the timestamped folders they all show all the files, now maybe I imagined this but Im sure before the only files in these folders were the files that had changed or new files ala incremental backup.

Am I going mad, do all your folders show all files?

Rich

RichB

Clearly I cant have that many folders with 95gb in them on a 500gb drive..

JackClark

Have a read of this AppleInsider | Road to Mac OS X Leopard: Time Machine I believe I understand it but can't explain it very well. I'm sure Markus will be along shortly.

Markus

Morning all. Firstly, I still have not got round to trying out Time Machine, I'm still using Retrospect, so I cannot say my setup looks the same. I'd certainly suggest posting/searching on the Apple discussion forums to see if others encountered this. My thought is that the other backup folders have hard links to files in the original backup and the Finder is treating those links as the real file and is resolving the link and finding the size of the original file and that is what is being reported back to you.

What I'd be inclined to do is to jump into the Terminal and then cd to one of the backup folders and do an ls -la and locate one of the files you know has not changed and see what it has for the filename, if it's listing something like nameoffile -> /path/to/nameoffile then I'd say it's a link to the file.

I'm going to configure TM on one of my dev machines in a moment and see if I get the same problem, thankfully it's only got the OS and dev tools on it so it's just a few GB of data so should backup quite quickly. I'll let you know what I see.

JackClark

They are hard links. There's a quite good explanation in the link I provided. My Time Machine drive looks pretty much the same.

RichB

In Terminal they all look like normal files, not symbolic links.

Thanks for the link Jack.

RichB

"Hard and Soft Links

Soft links are easy to understand and simple for users to employ; make an alias of a file, and it does everything that its target would do, while saved in another location. Multi-link files are a more complex idea, because they don't really fit the overall desktop metaphor. A Mac multi-link is a second "hard link" record that points to data or a directory. It doesn't just point to another file like an alias does; it is the same instance of that file. Create a hard link to a file, make changes to it, and the "previous file" is changed as well, because they are the same file. Delete it, and the file doesn't go away; it remains until the last hard link is removed. This is confusing in a quantum physics sort of way because it doesn't line up with the convenient physical metaphors we commonly use to visualize files and folders. "

"Regular files on any file system act as a single hard link. When you delete a file, you aren't really scrubbing the file off the disk, but rather only removing the hard link to it from its enclosing folder, banishing it to the unruly world of the unlinked wilderness of the drive. "Undelete" utilities attempt to search for unlinked files and restore them, but they can only work if the file system hasn't overwritten those unlinked files, which it will happily do without any concern, because the disk space consumed by unlinked files is fair game for recycling. "

RichB

I must have imagined it then, I could have sworn only the changes files were being shown in the later folders...

Markus

Rich,
I've just spoken to one of my dev chappies who is running Time Machine. What you are seeing is perfectly normal, and, as mentioned in the doc that Jack linked to, it's because TM is using hard links, which is essentially indistinguishable from a file — because it essentially *is* a file, It just, in this case (the files in the hourly backup folder), points to data that was already allocated for *another* file. Also, because of this, it will look like a normal file in the Terminal.

Bottom line, the hourly backup folders are NOT taking up a true 95GB of disk space. It is bloody confusing though. I guess Apple does not expect people to view the structure and simply use the Time Machine interface to view/access/retrieve the data in the backups.

JackClark

Time machine is great though, I only just found out that it worked with Address Book, saved my bacon... well almost, but that's another story. Any other apps? I know it works with Finder and Mail as well.