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Basic scenario: we are a school (overwhelmingly Mac, some Windows machines via BootCamp), and we are considering using DeepFreeze to guard the state of our shared machines. We have roughly 250 machines that are either shared laptops (which move around quite a bit) or common desktops in public spaces. Obviously, we spend a lot of time maintaining the machines and trying to reverse the inevitable drift as people make changes to the computers. We would like to control the integrity of the build we initially put onto the machines without handcuffing users and especially without using Mac's Parental Control software. (We've had nothing but bad experiences with it.)

We've been testing DeepFreeze, and so far it's very impressive. But I'm curious to hear if people who have used DeepFreeze or any similar software have any advice or tips. To get things started, I will post my own pros and cons.

Pros:

  1. The state of the machine is frozen in our chosen state. All changes made to the machine after that disappear upon restart. (This frozen state really appears to cover everything. I have yet to do something to a test machine that isn't instantly healed.) Tons of trivial but time-consuming maintenance is gone in an instant. Also, lots of not-so-trivial breakage should be avoided.
  2. There are good options, however, that allow you to create storage spaces either globally or per user. (Otherwise, stored files disappear upon reboot. For some machines, this is a good option itself. Simply warn people: save externally or else; this machine is a kiosk, not your storage space.)

Cons:

  1. Anytime we actually need to make a change (upgrade basic software, add a printer or an airport permanently, add new software), the process is a bit more complex. Reboot into a special mode (thaw state), make changes, reboot back into frozen mode. If (when?) we forget this, we will end up making changes that disappear after the next reboot.
  2. Users will forget to save files correctly (in the right place or externally), and we will have loud, unpleasant conversations explaining that we can't recover the document they worked on all afternoon yesterday. The machine rebooted. The file is gone.

These are my initial thoughts, but I would love to hear from other people who have experience with DeepFreeze or any similar software. What should we be careful about? Do the pros outweigh the cons? What gains or problems am I not seeing? Thanks.

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Instead of doing the complicated update process individually, have you considered building an image and using imaging software to roll out the updated image monthly/quarterly/whenever you need it? –  romandas Aug 6 '09 at 19:57
    
@Romandas: I'm not quite sure what you mean. If DeepFreeze is enabled, then it prevents you from overwriting it simply with a new image. We use imaging software for initial installations, but if we go with DeepFreeze, that will change what we can do after that. –  Telemachus Aug 7 '09 at 11:07

3 Answers 3

up vote 2 down vote accepted

I work as a sys admin in an engineering college. We set up all lab machines with Deep Freeze. We do have Mac (Snow Leopard) and Windows (XP and 7) machines. I have not personally installed the Deep Freeze client in OS X, but I'm sure it works similarly. We manage about 250 machines setup like this in total. Deep Freeze is a lifesaver.

All of these public computers get an admin account which we use for quick configuration, troubleshooting, etc., as well as a second admin account for students which has no password. As you said above, after restarting the machine any changes a student makes are lost which is extremely convenient. To remind users that any files they save will be lost upon restart, we post signs in every lab, and set a desktop picture that says this as well (highly recommended). Professors, TAs, and everyone else encourage the students to save their files in any of the following ways.

  • On their own flash drive
  • On the university provided network storage (however, it's slow)
  • On the university provided web server space (each student gets about 100 Mb)
  • Email the file to themselves
  • Upload to a web-based file storage service such as DropBox

For your administrative concern on having to thaw each machine for maintenance, the process is simple. You can use the Deep Freeze Console app to remote thaw and reboot machines. We use it to install a single new program in a lab for instance (a group of ~30 Windows machines). Changes are made machine-by-machine, and then the whole lot is remote frozen and rebooted in the Deep Freeze console. You are able to see in the console the status of every machine on the current subnet as well, which is helpful if one is missed. Faronics has a tutorial for the console app (warning: autoplay video).

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I know of at least one small University here in town that uses this setup. I don't know if they're using DeepFreeze specifically, but it sounds exactly the same (machine reboots and is restored to a specific state, saved files get wiped).

From my experiences there, the machines need a lot less maintenance than they would otherwise. They have printed signs at the library entrance (where the machines are located), and at each machine, warning users to save their work to a thumbdrive or e-mail it themselves before leaving, and that files will not be on the machine tomorrow to come back and work on, period. They will not attempt to recover your report that is due tomorrow. The users are college students, they need to learn to take responsibility for their work.

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I used to work in the tech department for a university library and we had a similar setup. We had public areas with computer and laptops that could be checked out. I actually did the DeepFreeze setup on the laptops (there were about 15). We had a warning screen on login that notified them of the data not being permanent. I worked in another tech shop w/ student labs w/ machines that we regularly reimaged. We also had a login warning screen. In both cases (for the students and university people) there were network drives for them to save data.

If you have network drives for users, it might be worthwhile to look into being able to change the default save area to the network drive. I'm sure there's a reg key or local policy for that.

Edit - Just noticed the Mac part. So, obviously no registry, but there should be some configuration somewhere to change the default save locations.

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