OSX-ZFS Testing update

[brendon....@mac.com]

All,

I am writing this brief post to let people know my experience with testing OSX-ZFS.

Background: I am a prior ZEVO user, and that was my stepping stone into the ZFS world. I brought thunderbolt hardware for ZFS, installed ZEVO, got it going nicely enough and then found out that it was not going to be immediately compatible with Mavericks. This meant that for me it was a bit of a dead end - so returned to HFS+ and started sniffing around the OSX-ZFS project.

Hardware: I have been testing OSX-ZFS for the last several weeks on three different Macs - a 2011 Macbook Pro, a 2009 iMac and most recently my main machine - a 2011 iMac with 32gb ram and a Lacie 5Big thunderbolt drive.

Goals: I want to be able to use ZFS as my users home directories, and also use ZFS via OSX Server for various storage tasks + hosting Time Machine backups for the other machines in the house. I have a lot of family media which would be irreplaceable, and if lost my wife would be not very happy to say the least. So to me ZFS gives me the ability to make a large "raid-like" storage device and convenient backups using ZFS snapshots, and I have have confidence that its not suffering from silent corruption.

Experience: I came to the project with the full knowledge that OSX-ZFS is a work in progress. And that is still true today. I have been focussing on desktop use testing, which has mostly focussed on stress testing as different failures and panics were triggered. In recent days with the landing of fixes to memory management and locking in the SPL, the implementation has become quite stable for me. I want to stress that even with the panics from testing, I have not managed to corrupt a ZFS data set. I have not been able to cause a panic with the latest code base.

Performance is something many people have asked me about - for me performance is consistent with software under development - there are some underlying issues still to be sorted. I am currently using a slightly older experimental version of their memory manager and it gives good performance (note: it's in a branch for a reason, there are limitations) on my main machine - conservatively I have seen bursts of >200mb/sec on large files using raidz2 to the Lacie.  I get a huge grin on my face hearing all 5 drives chattering away flat out.

I now have more that 1 TB of my family data installed on the Lacie using raidz2. Am now testing its use as a home directory more widely. I have a basic desktop running that I am quite happy with - iTunes, iPhoto, email and web browser. I have used word and pages and a few other applications on my home directory with no particular issues being identified. I know from ZEVO that there are Mac applications that won't work well, and expect that to be the same with OSX-ZFS.

I have done some brief experiments with l2arc using a USB 2.0 pen drive, and it did work. Obviously you need an SSD for it to be effective, and I hope to test that soon. I have not yet tried running with an SSD based ZIL, and will be interested to see how much more performance can be gained from that.

I am now confident enough with OSX-ZFS to put it into use on my machines. Obviously the software is under development still, I have found the support from the authors to be excellent with defects being resolved very quickly once properly diagnosed.

Thanks heaps to Lundman and ilovezfs for doing the hard work in creating a modern ZFS implementation for the mac.

- Brendon