Difference between revisions of "FAQ"

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(Q) Do HFS only applications such a photos, OSX server and others work on ZFS?)
(Q) Do HFS only applications such a photos, OSX server and others work on ZFS?)
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===Q) Do HFS only applications such a photos, OSX server and others work on ZFS?===
 
===Q) Do HFS only applications such a photos, OSX server and others work on ZFS?===
 
'''A)''' Sometimes. Apple codes some software to only work when stored on HFS. We can't change that. We have provided a property that causes ZFS filesystems to identify themselves as a HFS when enabled. After that there is a higher chance of the application working. The risk of course is that the application may malfunction due to some dependency on HFS specific behaviours that ZFS may not exhibit.
 
'''A)''' Sometimes. Apple codes some software to only work when stored on HFS. We can't change that. We have provided a property that causes ZFS filesystems to identify themselves as a HFS when enabled. After that there is a higher chance of the application working. The risk of course is that the application may malfunction due to some dependency on HFS specific behaviours that ZFS may not exhibit.
 
Applications that the FAQ author uses with HFS mimic:
 
* Photos
 
* OS Server
 
 
    
 
    
 
     sudo hfs set com.apple.mimic_hfs=on <dataset>
 
     sudo hfs set com.apple.mimic_hfs=on <dataset>

Revision as of 19:58, 23 October 2015


Besides the questions covered below, you may find Documentation and OpenZFS on OS X helpful. Both articles contain a good deal of information about OpenZFS on OS X.

General

Q) What is OpenZFS on OS X?

A) See the article entitled OpenZFS on OS X.

Q) What does O3X mean?

A) O3X = O O O X = OpenZFS on OS X.

Q) What version of ZFS do you use?

A) OpenZFS. Pool version 5000. File system version 5. Pool version 5000 is pool version 28 plus support for feature flags. We support pool version 5000 and pool versions less than or equal to 28. We do not support the closed-source Oracle Solaris ZFS pool versions 29 and up.

Best practices

Q) Do I have to use mirrors or raidz?

A) Have to? No. Should you? Virtually always. ZFS will not be able to repair errors it finds unless you have redundancy at the vdev level.

Q) Can I set copies=2 in lieu of using mirrors or raidz?

Setting copies=2 is a poor substitute for vdev-level redundancy. Two copies on a broken drive are worthless. That being said, yes, you can set copies=2. Do so at your own risk.

Administration

Q) How can I access the .zfs snapshot directories?

A) You need to set snapdir visible and manually mount a snapshot.

$ sudo zfs set snapdir=visible tank/bob
$ sudo zfs mount tank/bob@yesterday
$ ls -l /tank/bob/.zfs/snapshot/yesterday/

Q) Is .zfs snapdir auto-mounting supported?

A) No, not at this time. You must manually "zfs mount" snapshots manually to see them in the snapdir.

Q) OK, I manually mounted my snapshot but still cannot see it in Finder. What gives?

A) Currently mounted snapshots are only visible from Terminal, not from Finder.

$ ls -l /tank/bob/.zfs/snapshot/yesterday/

Q) Why does OSX server not allow the server storage to be on ZFS?

A) OSX Server has been coded in such a way as to only allow the server storage area to be an HFS formatted drive. O3X offers a feature that causes ZFS datasets to identify themselves as HFS. This is sufficient for OSX server to allow storage on a ZFS filesystem. HFS mimic is enabled by setting the com.apple.mimic_hfs property on a per dataset basis.

Interoperability

Q) How do I create an O3X compatible pool on another OpenZFS platform?

A) Only enable feature flags supported by O3X, as discussed here.

Q) Can I import my ZEVO pools?

A) Yes. O3X can import pool version 28, which means it can import ZEVO pools.

Q) Can I import my MacZFS pools?

A) Yes. O3X can import pool version 8, which means it can import MacZFS pools.

Q) Do HFS only applications such a photos, OSX server and others work on ZFS?

A) Sometimes. Apple codes some software to only work when stored on HFS. We can't change that. We have provided a property that causes ZFS filesystems to identify themselves as a HFS when enabled. After that there is a higher chance of the application working. The risk of course is that the application may malfunction due to some dependency on HFS specific behaviours that ZFS may not exhibit.

   sudo hfs set com.apple.mimic_hfs=on <dataset>

Limitations

Q) Can I use finder permissions aka ACLs?

A) Not yet. There is work to go in this area. See https://github.com/openzfsonosx/zfs/issues/275

Q) Can I boot my computer off of O3X?

A) No. O3X cannot be used as your main system partition.

Q) So if I use O3X, that means I don't need to back up, right?

A) Wrong. Wrong. Wrong.

Q) Does Spotlight work?

A) Yes. Spotlight works on O3X 1.3.1+.

Q) Can Time Machine backups be stored on ZFS?

A) Yes. It is possible to host a TimeMachine backup within a SparseImage on ZFS, or an HFS formatted ZVOL On ZFS.

Q) Can TimeMachine backup the contents of a ZFS volume?

A) No. We believe that when "Issue 116" is resolved it may be supportable. At the present time TimeMachine excludes ZFS filesystems from the list of available backup targets.