My midterm goal was porting libzpool -- which contains most of the ZFS code -- to Haiku. Another midterm goal was to get ztest -- the ZFS testing tool --- to run on Haiku. Being able to run ztest in a loop for an entire day means that about 80% of the ported code is working fine (though the remaining 20% is the most difficult part of the entire porting process). ztest is a userland test, so actual file system modules or disks are not involved in the testing procedure -- ztest creates block files in a temporary directory and treats them as disks.
This is a companion discussion topic for the original entry at https://www.haiku-os.org/blog/generalmaximus/2011-07-19_zfs_port_midterm_report/