Who is this article for?
CrashPlan for Small Business, no.
Code42 for Enterprise, yes.
Link: Product plans and features.
This article applies to version 4.
If you have an extremely large backup set and regularly add a lot of new files (for example, you are a professional photographer or filmmaker), you might want to back up to an external hard drive for convenient and faster restores. Some people rotate external hard drives between local and offsite locations, in case of a disaster that affects the entire local facility. When CrashPlan detects a new hard drive, it syncs with the new drive and continues the backup wherever the drive left off.
If you delete a file from your device that you backed up only to Drive A (but not Drive B), the backup of that file now only exists on Drive A. When you swap in Drive B, you cannot restore the deleted file from that drive.
Similarly, versions of files exist only on the original hard drive they backed up to. When you swap in a new drive, the latest version of a file will back up, but older versions that exist on Drive A will not be added to Drive B.
Back up to multiple destinations
CrashPlan does not limit how many destinations you can use. We recommend backing up to multiple destinations in addition to your external drives. See Choose multiple destinations for example configurations.
Seed your initial backup locally
(Code42 for Enterprise customers only)
If you have a large backup set, you can seed your initial backup locally, bring the backup to your offsite location, and then continue over the Internet from where you left off. Seeding makes automatic offsite backup a realistic option for people with slow connections, especially if one of your offsite locations is down the street or across town.
Once the initial backup is complete, it's easy to stay current, as CrashPlan automatically de-duplicates and compresses new files or changes to your existing files before they're backed up. This means the amount of data transmitted is comparatively very small.