I had an abrupt hard drive failure on my iMac recently. That drive has been replaced and I am working on restoring from my Time Machine backup saved to my Drobo 5N. Backing up has been going smoothly and reasonably fast. It improved a few months ago after I replaced a low quality Ethernet cable to my iMac.
I was not able to mount the Time Machine share via the command line for restoration. I installed a fresh copy of OS 10.11.6 and, not finding a better way to do it, loaded up the sparsebundle file and have transferred files manually. The initial loading of the disk image takes a while, but it is large and complicated, so I found this unsurprising. Once loaded, I was able to navigate to the latest backup and moved a number of folders over to my new hard drive. Here, each folder had a delay to load, but it was on the order of 20–60 seconds. Once I began transfers, they went at reasonable speeds.
At some point, an installation required a restart, and the disk image was unmounted. Since trying the same sequence again, I am finding load times incredibly slow. Transferring about 3 GB is going to take 12 hours plus hour or two for the disk image to load and for navigation through just a few folders.
I have the latest copy of 10.11, Drobo dashboard, and 5N firmware and none of those things changed from the initial transfer to now. One of the things that may have been installed in between is Sophos Home antivirus software. I have not found it to be a performance problem in the past. The rest of the recent installations don’t seem like they would cause this behavior. I also tried restarting the 5N and Mac at different times.
Does anyone have some thoughts on why things are slow and how to improve them? The initial experience was reasonable. This one makes me think I need to consider a different back up strategy. Intact and nearly unavailable is not the best backup.