CrashPlan is excellent cloud backup software. However, one issue it has is that it depends on Java, which is a transitional state on Macs. On Macs, CrashPlan is designed to work with Java 6, which is included with Snow Leopard, and downloaded from Apple if needed on Lion and Mountain Lion.
One complicated bit is that if you upgrade from Snow Leopard to Lion or Mountain Lion, CrashPlan will simply stop running, because Java isn’t there. You have to actually run the CrashPlan application, and then you’ll be asked if you want to install Java. Once you do, CrashPlan will resume.
But another complication is that the current version of Java is Java 7, and it is provided by Oracle, not Apple. In theory, CrashPlan now works with Java 7, but we have seen it do strange things, like generate a gigantic, disk-filling log file. So if you installed Java 7 from Oracle, CrashPlan may or may not be working right.
Fortunately, (Oracle) Java 7 coexists with (Apple) Java 6, rather than replacing it, and it’s possible to tell CrashPlan that it should continue to use Java 6, which was figured out here. What is suggested there is not for the technically inexperienced, so we made a little program, attached to this post, to allow you to make this change easy peasy. It will also assign more memory for CrashPlan to use, which we’ve found reduces crashes or CrashPlan stopping and restarting in some cases.
Here’s our simple app (click the link to download):