Quote Originally Posted by baryluk View Post
Very interesting article. This misaligment read can be becuase he was using disk slice/partition, not whole (recomended) disk. And partition could be possibly unaligned. I hope next zpool will include this parameter to be configured at creation, without needing to patch it.

I will test if my zfs is working correctly on one of 2TB WD *EARS disk.
From what I got from ZFS it will use the block size reported by the device and at least for the WD EARS hdds this is 512 byte. So even if you align your partitions perfectly to the 4k boundaries (or use the full hdd), you'll get <4k writes. In those cases the drive has to read the 4k block first before writing the changed part.