Switching from Zevo to OpenZFS on OS X

I recently moved my last Mac from Greenbytes Zevo to OpenZFS on OS X, the reason for both sticking with Zevo & switching to OpenZFS were one and the same, CPU usage.
Prior to the development of OpenZFS on OS X, the two choices for using ZFS on OS X where Zevo or MacZFS, Zevo originally started out as a commercial product but switched to a freebie after Greenbytes picked it up. Zevo had much better integration with OS X e.g disk would be automatically mounted when connected to system just like any other disk with a supported file system and it supported a v28 of the filesystem whereas MacZFS supported a much older version.

When the OpenZFS on OS X development began just over a year ago, I ran the test builds that where made available, though these supported new features through feature flags it was very early days, attempting to scrub a zpool on a i7 MacBook Air with a USB 3 disk would spike the CPU for the duration and again the integration was still missing, you manually had to import & export pools. I continued to try newer builds on my MacBook Air but stuck with Zevo on my 2007 MacBook Pro.

The two things which where annoying about Zevo was that it was a dead end, development had stopped, the last version available wasn’t compatible with Mavericks available and its conservative memory setting meant that disk performance wasn’t that great, during playing audio files it would break to buffer audio in iTunes for example (luckily not in Serato as mid set would’ve been embarrassing).

As the MacBook Pro was running low on disk space I tried to move around 40GB of files in several chunks in parallel to my external USB3 disk & noticed the CPU pegged and fans started up with Zevo too. OpenZFS on OS X is fairly robust now (though still rough around the edges) so I decided to switch over.

The OpenZFS on OS X disk image comes with uninstall scripts for Zevo & though the main script was unable to detect the installed copy of Zevo, I was able to run the subsequent scripts individually to remove Zevo from my system and reboot (eject the disk containing the filesystem beforehand (export the zpool)).

The integration with OS X is still missing though it seems that on boot zpools are imported, I’ve not worked out if that’s because the system caches the state from previous boot or this is the preliminary support for auto mounting???

If you want to eject a disk, you still have to export the pool manually from terminal, pressing the eject button in finder will remove the disk icon but the filesystem is still mounted. That aside, OpenZFS on OS X performed well, scrubbing the zpool on the 2007 MacBook Pro did not cause the CPU to spike at all, there is now a shorter delay in iTunes when starting to play a track but haven’t noticed any drops in audio yet, so things are looking positive.

Scrubbing the zpool on a 2007 17″ MacBook Pro with 4GB RAM

pool: tank
state: ONLINE
scan: scrub in progress since Fri Jul 25 18:58:48 2014
28.2G scanned out of 579G at 30.1M/s, 5h11m to go
0 repaired, 4.87% done
tank ONLINE 0 0 0
disk1s2 ONLINE 0 0 0

errors: No known data errors

All properties on the zpool I was using:
tank type filesystem -
tank creation Mon Jul 29 5:00 2013 -
tank used 579G -
tank available 1.22T -
tank referenced 579G -
tank compressratio 1.00x -
tank mounted yes -
tank quota none default
tank reservation none default
tank recordsize 128K default
tank mountpoint /tank default
tank sharenfs off default
tank checksum on default
tank compression off default
tank atime on default
tank devices on default
tank exec on default
tank setuid on default
tank readonly off default
tank zoned off default
tank snapdir hidden default
tank aclmode discard default
tank aclinherit restricted default
tank canmount on default
tank xattr on default
tank copies 1 default
tank version 5 -
tank utf8only on -
tank normalization formD -
tank casesensitivity sensitive -
tank vscan off default
tank nbmand off default
tank sharesmb off default
tank refquota none default
tank refreservation none default
tank primarycache all default
tank secondarycache all default
tank usedbysnapshots 0 -
tank usedbydataset 579G -
tank usedbychildren 4.48M -
tank usedbyrefreservation 0 -
tank logbias latency default
tank dedup off default
tank mlslabel none default
tank sync standard default
tank refcompressratio 1.00x -
tank written 579G -
tank logicalused 578G -
tank logicalreferenced 578G -
tank snapdev hidden default
tank com.apple.browse on default
tank com.apple.ignoreowner off default

Upgrading the zpool with OpenZFS on OS X
This system supports ZFS pool feature flags.

Successfully upgraded 'tank' from version 28 to feature flags.
Enabled the following features on 'tank':