I need to backup several servers & workstations for some clients, it is essential that they can't see each other.
Googling around I can't find a good solution, there are lot's of backup applications but none with everything I need?.
So I turn to Expertise - that's you, people at linuxquestions!

More in detail:
I'm running a small business - that is "self-employed" with some 5-10 clients. Mainly I'm a hired Sysadmin, but clients sometimes wants me to take care of everything including backups.
To make it easier for myself I want to install a backup-service on my server which handles backups for all clients. Every client must be able to handle his/her own backups without seeing other backups or other accounts!

So:
True multi-user, with client never knowing about other clients: Must-have.
GUI for clients, for selecting backup-files & restoring: Must-have. Preferably a web-solution where I just give each client an account.
GUI for admin: I don't really care
Free-as-in-beer: To begin with a Must-have. Don't mind paying later on when business is running better. Something with a free basic and a commercial pro-level would be terrific.
Can backup both Linux & Windows servers & desktops: Me want. I could of course use 2 backup applications if there isn't one single to meet my needs.
The only solution I've found that might meet my needs is Bacula, but all I'm reading is that it's pure h*ll to setup. And remember, I will not use it extensively so it can't be too complicated to setup.
Backuppc is very good, I'm running it today and I really like it, but it doesn't have multi-user support. (Maybe that can be fixed?...)

So, any suggestions?

Hi,

Not sure if I trully understand what you're lookinf for but...
seems to me that all you need is a (1) front end (web page for your clients to log in) and (2) play with rsync.

How about http://amanda.zmanda.com/ ?

From what I've read, Amanda doesn't have completely isolated user accounts.

Fair enough; most backup systems are designed to be run by a central sysadmin I suppose, so the solid-wall between "accts" isn't specifically catered for.
Its an interesting qn; I guess Web Hosters have a custom web frontend to a std backup system that just makes it look like its separated.
Do you know anyone (personally) in the hosting line you ask?

I guess you're right, I haven't been able to find any backup-system that does what I want - but there are several commercial services doing exactly the same.
I don't know anyone in the hosting business, but I'll pop a question to my LUG here in Uppsala. There are some clever folks there.

I'm also thinking of BackupPC: if I login with some other account - all that's needed to login is a htpasswd - I can't see any hosts or backups. Maybe there's a way to fiddle with it, probably using ACL then as all files belong to backuppc:backuppc.
If I can't find any other backup-system I'll set up a testing environment during Christmas holiday.
Could be really interresting, BackupPC is really great!