Bauer-Power SAN using SuperMicro hardware, Ubuntu and SCST. It works great! It works so great in fact that the storage we use for virtualization for my company's home office, our QA environment and our DR environment all use Bauer-Power SANs for storage.
Enough about that though, so how did we move away from tape? Well, a few years ago I discovered CrashPlan, and started using it with two 20TB Bauer-Power SANs. We would back things up to disk with CrashPlan, then back those archives up to tape once a week. It worked pretty good, but tapes are super slow.
Last year my CTO said he wanted to move away from tapes, so I came up with the plan to send one of the 20TB Bauer-Power SANs to our DR site in another state, and setup CrashPlan out there. Now all of our Production servers backup directly to our DR site, and since it is in another state, it is already securely offsite should something happen to our primary data center.
We also backup to our local CrashPlan server for faster recovery. CrashPlan lets you backup to multiple locations simultaneously.
CrashPlan is probably the most reliable backup solution I've ever used. I've used Backup Exec, Yosemite, Microsoft DPM and Arcserve Brightstore. All of them have had issues, but I never have those issues with CrashPlan.
Do you use disk only backups? What software do you use for that? Let us know in the comments!