ARCserve Disk-Based Device was set to Dedupe in which is unsupported and not recommended. The correct configuration is to use Windows File System
Other caveats using “deduplication device” created in “Device Configuration” in ARCserve then you are using ARCserve software deduplication before the data actually came to our device. This would have an impact on savings and likely performance as well. I can’t tell you why using software deduplication to us stopped working after the upgrade but I can tell you it wasn’t supported and we’d highly recommend against using it.