ZFS performance issue / isolating bottlenecks
I'm experimenting with ZFS but encountering perfomance issues.
Ubuntu 12.10 AMD64 live CD with zfs-fuse installed. 32GB RAM DDR3 1600MHz intel I3 2100. 4x 3TB of same model/make, 2 pools in stripe of 6TB. I'm copying the contents of pool 1 to pool 2. The disks of pool one are connected to SATA300, pool 2 is connected on SATA600. The software I use for the copy is midnight commander.
I see the progress bar progressing in mc but no write activity on pool2, then the progress bar stops, I see a lot of write on pool2 and finally the progress bar continues again.
I see the same kind of speeds/behaviour when I'm copying from a RAID array on an areca RAID controller to my mainboard so I guess it's not because both pools/devices are sharing the available bandwidth. I know the CPU isn't the best but I only rarely see peaks of 50% load so I guess that's not the bottleneck either.
I don't know whether this is an hardware issue or a ZFS tweak somewhere?
If you don't know anything about ZFS, you might be of help by telling what great method you use for spotting bottlenecks in systems