ZFS Resilver Observations

As it has been discussed on the ZFS mailing list recently (subscribe here), I figured I would post my most recent observations on resilver performance. My home server is an HP MicroProliant N36L (soon to be an N54L) with 8GB RAM, a Marvell based eSATA card (I forget which one), and a StarTech 4-drive external enclosure (which uses port multipliers). The system is running FreeBSD 9.1-RELEASE-p7. The zpool in question is a 5 drive RAIDz2 made up of 1TB drives, a mix of Seagate and HGST. Note that drives ada0 through ada2 are in the external enclosure and ada3 through...