Rsync and extended attributes

That's funny, I thought that an "@" sign meant that it was a symbolic link? I can't find the post, maybe you could linky it?

Anyway, I've done some research on extended attributes, and I now know what they are (please correct me if I'm wrong); an extra part that can be applied to any file and store any meta data that anyone cares to add. Basically, you can use it to be far more descriptive about a file that what's available in "Get info", and can look it up without having to open the file itself. Network admins seem to think this is a fantastic idea, as they can use the extended attribute to very specifically define who is and who isn't allowed access to files, but there's lots of other applications for this besides security. Here's a link with a pretty good explanation: http://arstechnica.com/reviews/os/macosx-10-4.ars/7

I'm not really sure how widely used extended attributes are. I can't seem to find any just by randomly looking through directories in console, making sure I use "ls -a" to list files with a leading "."; I think they should start with "._" and then the same filename as the file they refer to.

So it seems that extended attributes are different to Mac OS9 resource forks. However, I don't use OS9 anymore, so I'm not going to worry that the BSD-based NAS I'm using doesn't recognise these either. On the whole, I'm going to ignore both issues until someone tells me different!

Which brings me finally to Rsync. Gosh, it's annoying. The Apple implementation is flawed because of it's tacked on support for extended attributes. I didn't even try using it. I downloaded RsyncX and played around with that, even managed to do a backup of my important folders in my Users folder, but not without plenty of mysterious "Code 2" errors stopping the backup every so often (about every 500MB it transferred to the NAS). Once everything was on the NAS, I could do a single rsync batch of folders, and it would pass through the whole thing, only updating the things I'd changed - just like it was supposed to do. I'm going to have to read up more about how to set it up to automate the backup though. I have checked the contents of the backup and it all seems to be there, I can browse my iPhoto library from my PC, and the file sizes all seem about right. So I guess part of the job is done.

However, RsyncX also seems a little flaky, and support seems pretty non existent. I think I'm going to try the patched version from http://www.onthenet.com.au/~q/rsync/ which is apparently patched to work with non-OS X filesystems and copies the extended attributes properly. It may get over the problem of RsyncX stopping every so often too. I think in the end the best solution to backup a Mac, assuming you're trying to back it up onto a server and not an external HD, is to make sure that server is another Mac, and if you're going to use rsync, makes sure that the version is the same in both locations. Then you won't have to worry about extended attributes as it'll support them automatically.

Hi Alan

I've had a look at my iPhoto folder, and it seems just like a normal folder. I can't see any "@" or "+" on the attributes. I did this by using "ls -elR". I think this should show any extended attributes, and by doing it recursively (-R) I viewed the whole iPhoto folder tree. The "-l" shows the attributes. Not sure about "-e", in the "man ls" it says "-e Print the Access Control List (ACL) associated with the file, if present." Here's my iPhoto Library root directory, nothing odd looking to me! It isn't a package, just looks like a regular folder. Remember I'm using 10.4.10 not Leopard, that other thread they're all on Leo.

./iPhoto Library:
total 245288
-rw------- 1 Ian Ian 1434435 Oct 28 22:16 AlbumData.xml
drwx------ 3 Ian Ian 102 May 27 12:33 Data
-rw------- 1 Ian Ian 68 Oct 28 22:15 Dir.data
-rw------- 1 Ian Ian 20 Nov 13 2006 Library.data
-rw------- 1 Ian Ian 20 Nov 13 2006 Library.iPhoto
-rw------- 1 Ian Ian 14821323 Oct 28 22:16 Library6.iPhoto
drwx------ 4 Ian Ian 136 May 27 12:33 Modified
drwx------ 4 Ian Ian 136 May 27 12:33 Originals
-rw------- 1 Ian Ian 15618048 Oct 7 22:05 Thumb32Segment.data
-rw------- 1 Ian Ian 62459904 Oct 7 22:05 Thumb64Segment.data
-rw------- 1 Ian Ian 31232000 Oct 7 22:05 ThumbJPGSegment.data
-rw-r--r-- 1 Ian Ian 48 Oct 7 22:05 iPhoto.ipspot
-rw-rw-rw- 1 Ian Ian 0 Nov 13 2006 iPhotoLock.data

Maybe with Quicken you'll just have to get used to archiving the package to a zip file, then back that up. Were all the @ showing up on your 10.5 system? I notice you've switched back to 10.4.7 for your last post! I won't restore my iPhoto directory at the moment, but I'm going to rebuild another Mac, so I'll try and restore it to that in the next couple of days.