Last night I installed an HGST Deskstar NAS 4TB drive in depot to pair with the existing HGST Deskstar 4TB drive. I saved the existing data to a ZFS pool on kiva, then wiped the existing HGST Deskstar drive: unmounted the filesystem, deleted the partition, deleted the partitioning scheme.
If you’re doing this for the first time on FreeBSD 10.1 or later, don’t forget to enable ZFS (loading of the kernel module) and tell the system to mount ZFS pools at boot.
Enable ZFS kernel module at boot by adding to /boot/loader.conf:
zfs_load="YES"
Tell the system to mount ZFS pools at boot by adding to /etc/rc.conf:
zfs_enable="YES"
If you haven’t rebooted after changing /boot/loader.conf, you can load the kernel module manually:
# kldload zfs
Before getting started, I changed the default ashift setting to be more amenable to 4k drives:
# sysctl vfs.zfs.min_auto_ashift=12
I then created my ZFS pool. First I created the GPT partitioning scheme on each drive:
# gpart create -s gpt ada0 # gpart create -s gpt ada4
I then created a partition on each, leaving 1 gigabyte of space unused:
# gpart add -t freebsd-zfs -l gpzfs1_0 -b1M -s3725G ada0 # gpart add -t freebsd-zfs -l gpzfs1_1 -b1M -s3725G ada4
I then created the pool:
# zpool create zfs1 mirror /dev/gpt/gpzfs1_0 /dev/gpt/gpzfs1_1
I created my filesystem heirarchy. For now I only need my backups mount point. Since FreeBSD now has lz4_compress enabled by default, I can use lz4 compression. lz4 is considerably faster than lzjb, especially on incompressible data.
# zfs create -o compression=lz4 zfs1/backups
I then copied back the original data that was on the single HGST Deskstar 4TB drive. Since I had disabled TimeMachine on my desktop computer in order to move TimeMachine backups to the ZFS mirror, I re-enabled TimeMachine on my desktop and manually asked it to perform a backup. It worked fine and completed in less than 2 minutes since I hadn’t changed much on my desktop machine.