Working Around File Sharing's "Wall of 10"

- 2001.08.16

If you have ever set up a small Mac network, you know creating a server is as easy as pie (see Transferring Files from Your Old Mac to Your New One for more on this topic), and it's a snap to setup login names and passwords using Users and Groups. This function is called "Personal File Sharing" in the deep Apple documentation, but as your needs grow you will soon hit the "Wall of 10."

Apple designed personal file sharing for small work groups. To encourage upgrades to AppleShare IP or Mac OS X Server, they built in some limitations which money can alleviate.

Having no money, I had to create a workaround, and I thought others might be interested.

In my classroom last year, nine Power Mac computers were connected through the building's network to my server, a Quadra 700 decked out with 20 MB of RAM, an aging SyQuest 200 MB cartridge drive, and an external 1 GB LaCie SCSI drive, which was the workhorse drive of the system. (Aside: That squirrelly drive rattled all last year, buzzed, and clicked, until I finally broke down and opened the thing up and discovered it had a bad cooling fan - which I replaced, solving the problem. If the thing is out of warranty, go ahead and open it up! You'd be surprised what you can fix.)

Anyway, with nine computers on the network I never really encountered the "10 limit," so it wasn't until this fall, when I obtained several brand spanking new iMacs for the classroom, that I had to face reality: Everyone couldn't automatically be logged into the server simultaneously any more.

What is the "10 limit"? Built into Apple's file sharing system are the following limits:

• No more than 10 folders can be "share points" at one time. A "share point" is a folder or drive volume which appears on the network as a device you can connect to remotely. You can share many more than 10 folders within a single share point, but they cannot be logged into separately. So if you wanted to have a folder for every user, secure from other users' eyes, 10 is your limit.
• No more than 10 users can be connected simultaneously.
• No more than 100 users can be listed in your Users and Groups file. (Most teachers, at least in high school, have well over 100 students. I have 170 or so.)

Apple Knowledge Base Article 15460 describes these limits and compares the limits set for AppleShare IP. (I'm still not used to saying "Knowledge Base" instead of "TIL".) Most of the numbers go up if you use AppleShare IP. Licenses of various sizes are available. Normal humans can buy a 10-user license, a 500-user license, and an "unlimited" license. Educators can buy a 50 user license, but this is exactly the wrong size: too large for a single classroom, but too small for a department.

Given these limitations and 14 computers, I can no longer allow everyone to connect to the server and just sit there for 100 minutes, always connected. So here is how I am working around the limit.

1. I created a shared folder for each of my classes, using up 6 of the available 10 slots. This eliminates the problem of having individual logins, but it does mean that students will have to be better trained to avoid throwing away other people's work. A seventh shared folder is called "Today's Assignment" and contains URLs or settings files for the project in use that day.
2. I also created a user for each class period, such as "First period student" and assigned a password. This effectively avoids the 100-user limit as am using only nine users (six classes, my assistant, myself, and the tech.)
3. I made an alias of the shared folder while connected via a student machine, then copied the alias to all the other student machines. Double-clicking on the alias eliminates the "Chooser" and "AppleShare" and "zone" steps of logging in manually.
4. Students will be trained to log in via the alias when necessary, but also to disconnect once the files are moved to the local machine. Since only 10 can be connected simultaneously, they'll just have to take turns.

An alternative suggested to me was running two servers simultaneously. That might work, but it does prohibit the use of the "Today's Assignment" folder unless I struggle to keep both folders synchronized. It also takes up an ethernet port I'd rather use on a student machine.

This fall we will begin using the iBook cart labs Apple is so fond of advertising. Our carts will have 15 or so iBooks on each cart plus a base station and an iMac. Without floppy drives on the iBooks and iMacs, Apple should remove the 10-user limit - or at least extend it to 20 or 30 machines - so districts can work around the lack of a floppy, which always causes trouble with the PC people and the people who purchase the hardware. Yes, they can all surf, even through a single base station if necessary, but they can't save their work anywhere without cumbersome unnecessary steps which could be eliminated by having a server able to handle a classroom of machines without extra expense. You might argue that an AppleShare IP license is small change compared to all those nice iBooks, but the conditions of our tech grant require us to spend nearly every available penny on putting machines in classrooms; there's nothing left for such niceties as server software (or floppy drives, for that matter).

When the iBook carts are ready, I'll let you know how it works out.