[Grue3]

CrashPlan has unlimited backup and never deletes files. And keeps all the old versions of the files. I don't know how they stay in business, given that somebody probably uses it to backup petabytes of constantly changing data. They have pretty slow upload/download speeds though so perhaps something like Amazon Glacier is involved.

https://support.code42.com/CrashPlan/4/Restoring/Retaining_A...

[SyneRyder]

I was just about to say that CrashPlan is restricted to the internal drive of a computer & is therefore limited to the maximum size of hard drives (e.g. 1-2 Terabytes for laptops), but apparently CrashPlan lets you backup external drives now too:

http://support.code42.com/CrashPlan/4/Backup/Backing_Up_Exte...

[leejoramo]

Having used CrashPlan's personal offerings for many years, I recall that they have always allowed the backup of attached storage either from hard drives or network mounts.

[miahi]

The slow upload is also a way to limit the backup size. I currently back up >4TB on CrashPlan and it took a few months of 24/7 upload.

[leejoramo]

I was going to point to the ability to seed large backups to CrashPlan's cloud, but it doesn't look like this is an option anymore.

You can still seed to a private cloud of your own, friends and family, but not to CrashPlan's server.