Wish I could take credit, but I just customized this theme a little from the one I downloaded from here: http://wpthemepark.com/themes/paalam/

Due to Apple’s continuation of the HFS+ file system, Time Machine does not support block-level backups. If even one entry in a large data file changes, the entire new version of the large file must be backed up. Other backup solutions will simply back up the portion of the file that has changed. This missing feature has raised serious concerns; the main reason is because Macintosh users sometimes make use of virtualization; virtual disk images are very large and change every time they are booted, making it essentially impractical to include these disk images in Time Machine backups. Another reason for the concern is because some developers continue to use single database files to store data — a common example here would be Microsoft’s Entourage, which stores all email messages in a single file.

Wikipedia Time Machine Article.

I’m deleting all of the backups now, and starting over…hopefully have this thing humming today.

I wasn’t aware that you could permanently “switch” iTunes Library using option-click. Thanks for the tip!

I’m trying to figure out how in the hell my 80gb mbp and 80gb mac mini w/ 100gb of information on an external drive have managed to completely fill a 500gb external usb drive. I’m thinking there was some strangeness with things getting backed up from multiple places.

And…i’m not worried about having to ‘tell’ itunes where the library file is…were you talking about my ‘option-click’? You’ve only got to do that once…once itunes is looking at the library, it’s there…of course, a symlink will work, but so does this way…

This works exceptionally well with the iPhoto Library. We easily shared and edited the same iPhoto Library from two different computers using a Symlink. Neither computer actually had the Library local, either. Both had Symlinks pointing to the Library on a local share. Worked like a charm, as long as you don’t both try to edit the Library at once.

PS: Fixed that link, thx.
PPS: Don’t you just hate rsync?!

After looking around, I just went with two 500gb mybooks, one of them as the time machine backup, and one of them as the file repository. these are both usb connected to the mac mini, which will be up and running about 98% of the time…so, eventually, i’ll set up some way to access this from the web, via a secure http connection of some sort. i’ve already installed the ultra-geek-cool tomato, and have linked it to a dyndns account, so i’ve got an address to go to once i get it set up (as my ip changes every once in a while from the cable company, that’s my best bet).

Two cheapo usb drives (i got them as refurbs from ecost for $99 each) were a lot more cost effective than any nas i could think of, and once I factored in time machine, i wasn’t too worried about having raid.

so, as I mentioned, i played with rsyncx for about 15 minutes, and it was confusing as hell. not to mention that when i *could* get it to sync, it would only do so when i entered the password…couldn’t figure out a way to just whisk it on its way w/o having to enter password every time.

another problem was that this is syncing to a laptop (obviously, but bear with me)…at night, i want to close my laptop, thereby making it impossible to sync from/to.

the best option that I could think of would be to somehow have a trigger that would sync to/from the laptop whenever it is detected on the network. I’m sure that can be done, with a nice bit of scripting, but I’m certainly not going to be the one who can do that.

At this point, what I decided to do was (and this is a bit convoluted):

store all of the mp3′s on the external drive, connected to the mini. have a library file, on the mbp, that looks at those mp3′s, but the library is stored on the library. on the mac mini, have it look at the library file on the MBP (option-click when opening itunes on the mini…i know you know that, but i’m saying it for posterity).

why the hell did i do it that way? well, if i leave the house, and ever want to sync the ipod, the mbp will be with me. I don’t need to have the actual mp3 *files* on the mbp, but the library file must be accessible from the mbp, or else i wouldn’t be able to sync/download new podcasts/etc.

In that vein, I have decided to keep the iphoto library on the mbp, so when i plug in the good ol’ nikon d40 whilst on vacation, it will sync to the mbp’s iphoto library…as apple has made the iphoto library a package, i don’t want to deal with figuring out how to consolidate two libraries, so i can’t exactly set it up to work exactly like the itunes does…oh well, the mbp is still time machining to the drives connected to the mac mini…so if it dies completely, i’ll still have the photos at home.

I really think that rsyncx will be the thing that will work best for me…being able to update with the latest file will be nice…i’ll play with the symlink…thanks for the info.

oh, your link to ‘automount maker’ is busted…

keep it real, man….:) thanks again for the input…I’ll be back to expound if i figure out anything new.

Solution A:
If you can live with one very restrictive caveat, the easiest way to do what you want is a Symlink:

- A NAS will work fine for hosting your media library on your network — even over 802.11G, provided the playback machine allows for a few seconds of buffering to make up for any interference (like someone turning on a microwave somewhere and stalling your network). If you can’t arrange for playback buffering, I’d recommend going old school, and running a good CAT5E cable.

- Copy your iTunes library folder onto the NAS, and create a Symlink on each Mac that points the local “iTunes Library” to that remote folder. Use SymbolicLinker to make your job really easy.

- Its important that the music/video files referred to in the library are resolvable from ALL locations, so they must also be on a network share.

- Use Automount Maker, or some other solution, to ensure that your NAS is mounted every time each computer boots up (you’ll need to manually ensure that your MacBook Pro mounts the share, obviously, when it travels back into your network)

Under this scenario, changes made in each iTunes library will be reflected in all machines running iTunes off that library. HOWEVER, the critical caveat is that only one computer can have iTunes running at a time.
This was a deal breaker for me, since I wanted to have different instances of iTunes running in each room. It appears that iTunes locks the library on startup (or probably on the first edit — including accumulating playcounts) and other instances of iTunes won’t be able to work against a locked library.

Solution B:
If you can’t live with the above solution because, your next best bet is rsync.

I have searched high and low, and have not found sufficient information online to properly configure a two-way rsync. But the way it should work, if you can figure out the right switches to apply, is that it compares two folders — even over a network — and merges all changes between them. Meaning you can edit your iTunes library in both places, and on the next rsync they will be synchronized.

You’ll likely want to schedule rsync to run at night, either as a cron job, or through an AppleScript, scheduled with iCal. The advantage I’ve found to a nightly AppleScript is that I can automate other maintenance tasks nightly.

rsync is a part of the OS X distro, but apparently the version Apple included has some problems. You should be able to find info about rsync_hfs online, or you could try out the RSyncX GUI — which is only marginally less difficult to understand.

At this point, I have to shut-up, because I’m out of expertise. I would be very interested in hearing from you if you find a solution, or if you get rsync working. Its a very powerful command line tool, loved by many geeks. But unfortunately information about its two-way sync capability seems to be sparse and difficult to understand.

Please let us know if you make any progress on this — I wish Apple would come up with a simple and elegant way to do this for us!