Time Machine for shared group folders

Question

Hi,
I would like to set up time machine for a shared group folder on the server. I would like users to be able to use time machine from clients to see backup history of files in the group folder. Is this possible? How?
Gregor

Answer 1

+...would like users to be able to use time machine from clients to see backup history of files in the group folder. Is this possible? How?+
Yes. This is possible, but it isn't touted as one of the features that sells Mac OS X Server. The advertised Time Machine server solution is to host an AFP share point on the Mac OS X Server system which clients then use as a Time Machine backup destination, similar to Time Capsule.
But, what I think you're going for is something like this: You have a share point where multiple users can read and write, and you'd like the server to be able to backup that share point via Time Machine, but also allow its clients to connect and see those backups. This is kind of like "Time Machine for a sharepoint." Again, this isn't really touted, but it's possible. Here is an example which shows you how.
For starters, let's say that your server's disks are well-organized. You have one volume for the server's operating system (Boot), one volume for the share points (Data), and one volume for backup (Backup). Other scenarios could work, but this configuration will make this how-to easier to understand. Let's also agree that your server's hostname is junglecat.amazon.private.
Let's say that the share point (group folder) that we want backed-up is at /Volumes/Data/Group-Folder on the server. Let's also agree that your group members already have access to this folder - e.g. it is already a share point with an ACL entry that grants the group members read and write access.
You'll need to configure Time Machine on the server itself first, just as if it were a client. Open System Preferences, and use the Time Machine pane to choose the Backup volume as the server's backup destination. You'll want to make sure that only the contents of the Data disk (the disk housing the Group-Folder) are backed up. Skip anything on your boot disk, as you're using Time Machine to back up just the share points. Let the server at least start its first backup, which will create the following directory:
/Volumes/Backup/Backups.backupdb/junglecat.amazon.private
...where the server's Time Machine backups will be stored.
Now use Server Admin's File Sharing section to make the /Volumes/Backup disk a share point, with these properties: Share the folder via AFP, and enable it as a Time Machine backup destination. (Your clients will not really be backing up to the folder, but they will be needing to see it as a place that Time Machine can keep a backup. This creates the .com.apple.timemachine.supported file on the share point.)
It's also a good idea to disable guest access and add an ACL deny rule to the share point (/Volumes/Backup) which denies delete and delete_child for everyone:
chmod +a "everyone deny delete,delete_child" /Volumes/Backup.
This prevents people from storing other data next to the Backups.backupdb folder. The Backups.backupdb folder already contains an ACL deny rule that limits its access to read-only.
Back on a client, mount the newly-shared Backup share point. The client's Time Machine may ask permission to use this as a backup location (because it was defined as such), but don't let it. The important thing is that the client recognized it as a backup location.
To browse the server's Time Machine history, the client must right-click on the Time Machine icon in the Dock (or use the Time Machine menu extra) and choose "Browse Other Time Machine Disk," where the user can choose the server's backup volume. Now the client can go back in time on the server, star-field and all. If the user needs to restore a file, Time Machine will ask him/her where to save the restored copy; it will not overwrite the copy on the Group-Folder share point.
Hope this helps!
--Gerrit