I'm running a G3258 Intel Processor, B85 motherboard and 16GB of ram in my OMV for a number of years. Recently I changed from a 2x4GB ZFS mirror setup to a 6x2GB ZFS Z2 setup. Because I needed more Sata ports I installed a Dell H200 Perc raid controller, flashed to IT mode. When transferring my data back I realized something may not be right as it tool longer than expected. It wasn't until I tried using Rsnapshot to backup the data to the 4GB drive(s) I realized something is horribly wrong. The first 10GB transfer very quickly and then it starts slowing down, slower and slower. After 12 hours of transfer it's barely moving, drive activity is minimum and the size in the file system takes forever to go up. Now the interesting bit.....if I stop the transfer and start it up again it does not continue at the better speed. Further more if I select any other file on the 6x2GB array, for example a 1GB file, and copy it to another internal drive it sits for a long time. I didn't wait to see how long, after 10minutes I gave up because clearly something is wrong. At this point I can't even load any files off the array. To fix the issue, I have to reboot OMV.
I'm thinking I'm either dealing with some compatibility issue with the Dell H200 Perc Raid controller and OMV or my ZFS Z2 array has some serious problem. I'm thinking it's the first one because though I don't know how to benchmark a ZFS file system, I know it can do 100MB/s over the network. CPU usage is low, memory usage is fine. Any ideas how to tackle a problem such as this?