OpenZFS on OS X - User contributions [en]

Getting involved

2023-04-07T05:21:38Z

Zfsfan:

[[Category:About O3X]]
Getting involved and contributing benefits not only the community member and their fellow O3X users, but all users of [[Wikipedia:Free and open source software|free and open source software]].

This article describes how both new and experienced O3X users can contribute to the community. Note that this is not an exhaustive list.

== Official OpenZFS on OS X projects ==

=== Post on the forums ===

One of the easiest ways to get involved is participating in the [https://openzfsonosx.org/forum/ O3X Forums], which allow O3X users to get to know the community and help each other.

=== Improve this wiki ===

[[AboutWiki|O3XWiki]] is collaboratively maintained O3X documentation. All users are encouraged to [[O3XWiki:Contributing|contribute]].

=== Join the chatroom ===

You can help other users to solve problems in the [[IRC channel|IRC Channel]].

=== Fix and report bugs ===

Reporting and fixing bugs on the [https://github.com/openzfsonosx/openzfs/issues bug tracker] is one of the possible ways to help the community.

When reporting errors, please ensure that you include sufficient contextual information to assist with reproduction, diagnosis and resolution of the issue. At a minimum consider describing what you were doing, how repeatable the issue is, all text from the stack dump, what OSX version, and what O3X version you are running.

If you are experiencing panics, please turn keepsyms on (https://openzfsonosx.org/wiki/Install). This will make the stack dumps human readable, thereby improving our ability to diagnose.

If you are deadlocking O3X, please run the spindump command after O3X deadlocks and before the machine becomes unusable and post the resulting output. There is often a narrow window of time to do this. Spindump needs to run with elevated permissions using sudo. Normally only administrators can do this.

#sudo spindump
Password:
Sampling all processes for 10 seconds with 10 milliseconds of run time between samples
Sampling completed, processing symbols...
Spindump analysis written to file /tmp/spindump.txt

Copy the output file to an hfs filesystem and reboot.

For real time assistance please see us on IRC, there is usually someone online that can help (https://openzfsonosx.org/wiki/IRC_channel)

=== Code ===

Developers of all levels of experience and skill are encouraged to come talk about how they can contribute in the [[IRC channel|IRC Channel]] and on the [https://openzfsonosx.org/forum/viewforum.php?f=24 OpenZFS on OS X Development] forum.

Main Page

2023-04-01T15:31:21Z

Zfsfan:

__NOTOC__ __NOEDITSECTION__
'''Welcome to the [[O3XWiki:About|O3XWiki]]: your source for [https://openzfsonosx.org OpenZFS on OS X] documentation.'''

Often-referenced instructions can be found '''[[Documentation|here]]'''.

To submit a bug report, please follow the instructions '''[[Getting_involved#Fix_and_report_bugs|here]]'''.

(If you were looking for information about the MacZFS project, you should use their site instead: [http://code.google.com/p/maczfs/ http://maczfs.org].)
==The Software==

<div style="float: left; margin-right: 1%; width: 49%;">

; [[OpenZFS on OS X]]: Brief overview of OpenZFS on OS X.

; [[Downloads]]: Latest release of the Mac installer.

; [[FAQ]]: List of common and frequently asked questions.

; [[Documentation|O3X Documentation]]: Index of popular articles and often-referenced information about O3X and OpenZFS.

; [[Changelog]]: Bug fixes, new features, etc.

</div>
<div style="float: left; width: 50%;">
; [[Install|Installation Guide]]: Detailed guide through the whole process of installing OpenZFS on OS X.

; [[Uninstall|Uninstallation Guide]]: How to remove O3X from your computer.

; [[Development]]: Information of particular interest to developers.

; [[Performance]]: Performance and Benchmarking

; [[Source code|Source Code]]: Show me the code.

; [[Versioning]]: Version numbers of releases, pkgs, upstream, etc.
</div>

<div style="clear: both;"></div>

==Our Community==

<div style="float: left; margin-right: 1%; width: 49%;">
; [[Getting involved|Getting Involved]]: Describes various ways O3X users can contribute to the O3X community.

; [[O3XWiki:Contributing]]: If willing and able to contribute to the wiki, please see this article for ideas.

; [[Help:Editing]]: Technical Information about editing and contributing to the OpenZFS on OS X Wiki.
</div>

<div style="float: left; width: 50%;">

; [[O3X forums|O3X Forums]]: General technical assistance for users and discussion of all things O3X including development.

; [[IRC channel|IRC Channel]]: Live problem-solving and conversation with your fellow O3X users and developers '''#openzfs-macos'''.

; [[Beyond our walls|Beyond Our Walls]]: How to get connect more broadly with users and developers of OpenZFS on other platforms.
</div>
<div style="clear: both;"></div>

== Contact Us ==

<div style="float: left; margin-right: 1%; width: 49%;">

; [[O3XWiki:Administrators]]: Contact one of the admins by email.

</div>

<div style="float: left; width: 50%;">

; [[O3XWiki:Donations]]: Donations and other ways to contribute
</div>
<div style="clear: both;"></div>

==Twitter==
[https://twitter.com/openzfsonosx @openzfsonosx] on Twitter.

<html><a class="twitter-timeline" href="https://twitter.com/openzfsonosx" data-widget-id="444275713776951296">Tweets by @OpenZFSonOSX</a>
<script>!function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0],p=/^http:/.test(d.location)?'http':'https';if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src=p+"://platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs");</script>

<span>
<br>
<a href="https://twitter.com/openzfsonosx" class="twitter-follow-button" data-show-count="true">Follow @openzfsonosx</a>
<br>
<a href="https://twitter.com/share" class="twitter-share-button" data-via="OpenZFSonOSX">Tweet</a>
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Main Page

2023-04-01T15:30:52Z

Zfsfan: Quick link to instructions for bug reports

__NOTOC__ __NOEDITSECTION__
'''Welcome to the [[O3XWiki:About|O3XWiki]]: your source for [https://openzfsonosx.org OpenZFS on OS X] documentation.'''

Often-referenced instructions can be found '''[[Documentation|here]]'''.

To submit bug report, please follow the instructions '''[[Getting_involved#Fix_and_report_bugs|here]]'''.

(If you were looking for information about the MacZFS project, you should use their site instead: [http://code.google.com/p/maczfs/ http://maczfs.org].)
==The Software==

<div style="float: left; margin-right: 1%; width: 49%;">

; [[OpenZFS on OS X]]: Brief overview of OpenZFS on OS X.

; [[Downloads]]: Latest release of the Mac installer.

; [[FAQ]]: List of common and frequently asked questions.

; [[Documentation|O3X Documentation]]: Index of popular articles and often-referenced information about O3X and OpenZFS.

; [[Changelog]]: Bug fixes, new features, etc.

</div>
<div style="float: left; width: 50%;">
; [[Install|Installation Guide]]: Detailed guide through the whole process of installing OpenZFS on OS X.

; [[Uninstall|Uninstallation Guide]]: How to remove O3X from your computer.

; [[Development]]: Information of particular interest to developers.

; [[Performance]]: Performance and Benchmarking

; [[Source code|Source Code]]: Show me the code.

; [[Versioning]]: Version numbers of releases, pkgs, upstream, etc.
</div>

<div style="clear: both;"></div>

==Our Community==

<div style="float: left; margin-right: 1%; width: 49%;">
; [[Getting involved|Getting Involved]]: Describes various ways O3X users can contribute to the O3X community.

; [[O3XWiki:Contributing]]: If willing and able to contribute to the wiki, please see this article for ideas.

; [[Help:Editing]]: Technical Information about editing and contributing to the OpenZFS on OS X Wiki.
</div>

<div style="float: left; width: 50%;">

; [[O3X forums|O3X Forums]]: General technical assistance for users and discussion of all things O3X including development.

; [[IRC channel|IRC Channel]]: Live problem-solving and conversation with your fellow O3X users and developers '''#openzfs-macos'''.

; [[Beyond our walls|Beyond Our Walls]]: How to get connect more broadly with users and developers of OpenZFS on other platforms.
</div>
<div style="clear: both;"></div>

== Contact Us ==

<div style="float: left; margin-right: 1%; width: 49%;">

; [[O3XWiki:Administrators]]: Contact one of the admins by email.

</div>

<div style="float: left; width: 50%;">

; [[O3XWiki:Donations]]: Donations and other ways to contribute
</div>
<div style="clear: both;"></div>

==Twitter==
[https://twitter.com/openzfsonosx @openzfsonosx] on Twitter.

<html><a class="twitter-timeline" href="https://twitter.com/openzfsonosx" data-widget-id="444275713776951296">Tweets by @OpenZFSonOSX</a>
<script>!function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0],p=/^http:/.test(d.location)?'http':'https';if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src=p+"://platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs");</script>

<span>
<br>
<a href="https://twitter.com/openzfsonosx" class="twitter-follow-button" data-show-count="true">Follow @openzfsonosx</a>
<br>
<a href="https://twitter.com/share" class="twitter-share-button" data-via="OpenZFSonOSX">Tweet</a>
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Main Page

2023-03-27T13:59:28Z

Zfsfan:

__NOTOC__ __NOEDITSECTION__
'''Welcome to the [[O3XWiki:About|O3XWiki]]: your source for [https://openzfsonosx.org OpenZFS on OS X] documentation.'''

Often-referenced instructions can be found '''[[Documentation|here]]'''.

(If you were looking for information about the MacZFS project, you should use their site instead: [http://code.google.com/p/maczfs/ http://maczfs.org].)
==The Software==

<div style="float: left; margin-right: 1%; width: 49%;">

; [[OpenZFS on OS X]]: Brief overview of OpenZFS on OS X.

; [[Downloads]]: Latest release of the Mac installer.

; [[FAQ]]: List of common and frequently asked questions.

; [[Documentation|O3X Documentation]]: Index of popular articles and often-referenced information about O3X and OpenZFS.

; [[Changelog]]: Bug fixes, new features, etc.

</div>
<div style="float: left; width: 50%;">
; [[Install|Installation Guide]]: Detailed guide through the whole process of installing OpenZFS on OS X.

; [[Uninstall|Uninstallation Guide]]: How to remove O3X from your computer.

; [[Development]]: Information of particular interest to developers.

; [[Performance]]: Performance and Benchmarking

; [[Source code|Source Code]]: Show me the code.

; [[Versioning]]: Version numbers of releases, pkgs, upstream, etc.
</div>

<div style="clear: both;"></div>

==Our Community==

<div style="float: left; margin-right: 1%; width: 49%;">
; [[Getting involved|Getting Involved]]: Describes various ways O3X users can contribute to the O3X community.

; [[O3XWiki:Contributing]]: If willing and able to contribute to the wiki, please see this article for ideas.

; [[Help:Editing]]: Technical Information about editing and contributing to the OpenZFS on OS X Wiki.
</div>

<div style="float: left; width: 50%;">

; [[O3X forums|O3X Forums]]: General technical assistance for users and discussion of all things O3X including development.

; [[IRC channel|IRC Channel]]: Live problem-solving and conversation with your fellow O3X users and developers '''#openzfs-macos'''.

; [[Beyond our walls|Beyond Our Walls]]: How to get connect more broadly with users and developers of OpenZFS on other platforms.
</div>
<div style="clear: both;"></div>

== Contact Us ==

<div style="float: left; margin-right: 1%; width: 49%;">

; [[O3XWiki:Administrators]]: Contact one of the admins by email.

</div>

<div style="float: left; width: 50%;">

; [[O3XWiki:Donations]]: Donations and other ways to contribute
</div>
<div style="clear: both;"></div>

==Twitter==
[https://twitter.com/openzfsonosx @openzfsonosx] on Twitter.

<html><a class="twitter-timeline" href="https://twitter.com/openzfsonosx" data-widget-id="444275713776951296">Tweets by @OpenZFSonOSX</a>
<script>!function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0],p=/^http:/.test(d.location)?'http':'https';if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src=p+"://platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs");</script>

<span>
<br>
<a href="https://twitter.com/openzfsonosx" class="twitter-follow-button" data-show-count="true">Follow @openzfsonosx</a>
<br>
<a href="https://twitter.com/share" class="twitter-share-button" data-via="OpenZFSonOSX">Tweet</a>
</span>
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Main Page

2023-03-27T13:59:16Z

Zfsfan: Direct link to documentation (avoiding long searches)

__NOTOC__ __NOEDITSECTION__
'''Welcome to the [[O3XWiki:About|O3XWiki]]: your source for [https://openzfsonosx.org OpenZFS on OS X] documentation.'''

Often-referenced instruction can be found '''[[Documentation|here]]'''.

(If you were looking for information about the MacZFS project, you should use their site instead: [http://code.google.com/p/maczfs/ http://maczfs.org].)
==The Software==

<div style="float: left; margin-right: 1%; width: 49%;">

; [[OpenZFS on OS X]]: Brief overview of OpenZFS on OS X.

; [[Downloads]]: Latest release of the Mac installer.

; [[FAQ]]: List of common and frequently asked questions.

; [[Documentation|O3X Documentation]]: Index of popular articles and often-referenced information about O3X and OpenZFS.

; [[Changelog]]: Bug fixes, new features, etc.

</div>
<div style="float: left; width: 50%;">
; [[Install|Installation Guide]]: Detailed guide through the whole process of installing OpenZFS on OS X.

; [[Uninstall|Uninstallation Guide]]: How to remove O3X from your computer.

; [[Development]]: Information of particular interest to developers.

; [[Performance]]: Performance and Benchmarking

; [[Source code|Source Code]]: Show me the code.

; [[Versioning]]: Version numbers of releases, pkgs, upstream, etc.
</div>

<div style="clear: both;"></div>

==Our Community==

<div style="float: left; margin-right: 1%; width: 49%;">
; [[Getting involved|Getting Involved]]: Describes various ways O3X users can contribute to the O3X community.

; [[O3XWiki:Contributing]]: If willing and able to contribute to the wiki, please see this article for ideas.

; [[Help:Editing]]: Technical Information about editing and contributing to the OpenZFS on OS X Wiki.
</div>

<div style="float: left; width: 50%;">

; [[O3X forums|O3X Forums]]: General technical assistance for users and discussion of all things O3X including development.

; [[IRC channel|IRC Channel]]: Live problem-solving and conversation with your fellow O3X users and developers '''#openzfs-macos'''.

; [[Beyond our walls|Beyond Our Walls]]: How to get connect more broadly with users and developers of OpenZFS on other platforms.
</div>
<div style="clear: both;"></div>

== Contact Us ==

<div style="float: left; margin-right: 1%; width: 49%;">

; [[O3XWiki:Administrators]]: Contact one of the admins by email.

</div>

<div style="float: left; width: 50%;">

; [[O3XWiki:Donations]]: Donations and other ways to contribute
</div>
<div style="clear: both;"></div>

==Twitter==
[https://twitter.com/openzfsonosx @openzfsonosx] on Twitter.

<html><a class="twitter-timeline" href="https://twitter.com/openzfsonosx" data-widget-id="444275713776951296">Tweets by @OpenZFSonOSX</a>
<script>!function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0],p=/^http:/.test(d.location)?'http':'https';if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src=p+"://platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs");</script>

<span>
<br>
<a href="https://twitter.com/openzfsonosx" class="twitter-follow-button" data-show-count="true">Follow @openzfsonosx</a>
<br>
<a href="https://twitter.com/share" class="twitter-share-button" data-via="OpenZFSonOSX">Tweet</a>
</span>
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Stopping Spotlight etc. from changing ZFS without permission

2023-03-27T13:54:24Z

Zfsfan: link with further instructions to remove/prevent metadata

== The Issue ==

ZFS is a great solution for backing up data, and moving data between platforms (e.g. Linux and Mac OS X). However, if you connect an external ZFS drive to Mac OS X, you may be unpleasantly surprised to find that Spotlight, Finder etc. will modify the filesystems on the drive without asking (and even in violation of the user privileges granted by those filesystems). This goes against several basic principles that you probably expect:

* the filesystem should not change unless you change data on the filesystem. E.g. simply plugging in the drive should not change the filesystem.

* any attempted changes to the filesystem should obey the privilege rules set on that filesystem. E.g. if the current user plugging in the drive lacks write privileges to the filesystem, no changes should be allowed.

However, Spotlight, Finder etc. do not obey these expectations. This can lead to serious problems for standard ZFS activities such as snapshot based backup. For example, say you backup data by sending ZFS snapshots from one ZFS filesystem to another ZFS drive. When you try to push incremental snapshots to an existing filesystem, it may fail with messages like "data has been changed since snapshot XYZ" -- even if you never wrote to that backup filesystem since your last snapshot. Now you are in a quandary. You will have to manually investigate the backup filesystem(s) to see what all the changes are, and whether might be any changes that need to be preserved (rather than just rolled back). If you are used to working with ZFS on Linux this may initially baffle you, because on Linux a ZFS filesystem will not change in content unless you deliberately write data to it!

The following Mac OS X services will modify your ZFS filesystems silently:

* Spotlight
* Finder (.DS_Store, Trash)

== Solutions ==

* in general, if you are connecting an external ZFS drive to a Mac solely to READ data from it, '''just import it readonly'''. This is the one trivially easy way to avoid the whole problem, e.g.:

'''zpool import -o readonly=on tank'''

If that is not an option, then you are going to have clean up your ZFS filesystems (every time) after OS X has "dirtied" them:

* '''always take a snapshot of ZFS filesystems BEFORE plugging them in to a Mac'''. This makes it relatively easy to know which changes are "OS X dirt" vs. previous data changes that you made before plugging into the Mac, and to rollback the dirt. For example: '''zfs diff -H tank@lastsnap tank''' will give you a list of new, modified and deleted files since lastsnap. Use Google to learn what Spotlight and Finder's hidden file names are.

* if you did not deliberately make changes to a given ZFS filesystem while connected to the Mac, then '''just rollback to the latest snapshot''' (as your first action once you import that drive to a non-Mac host).

* add "flag files" to each file system to prevent various OS X services from dirtying them. E.g. '''touch /tank/.metadata_never_index''' should [http://superuser.com/questions/1000280/disable-ds-store-spotlight-and-other-metadata-on-mac-disk-image prevent Spotlight indexing]. We should collect a list here of all the rules for preventing such "dirty" services ([https://apple.stackexchange.com/a/7135 further instructions]).

A more extensive approach to add "flag files" and disable macOS services from polluting the file system:

# set the name of your ZFS pool on macOS, e.g.
zpool_name=tank

# Remove macOS specific files from Spotlight, fseventsd, and the Trashes, create dummy files instead
sudo rm -rfv /Volumes/$zpool_name/.{,_.}{fseventsd,Spotlight-V*,Trashes}
sudo mkdir -pv /Volumes/$zpool_name/.fseventsd
sudo touch /Volumes/$zpool_name/.fseventsd/no_log /Volumes/$zpool_name/.metadata_never_index /Volumes/$zpool_name/.Trashes

# Turn off Spotlight indexing and remove the .Spotlight-V* folders in newer macOS versions
sudo mdutil -i off /Volumes/$zpool_name
sudo mdutil -X /Volumes/$zpool_name

# Optionally, change ownership to current user to enable zfs volume operations w/o sudo
sudo chown -R "$USER" /Volumes/$zpool_name

Zpool

2023-03-21T01:37:30Z

Zfsfan: /* Creating a pool */ bugfix

Run '''diskutil list''' command to make sure you pick the correct disk before attempting to create your pool. Look under IDENTIFIER. Note that if you partition the disk yourself, and specify a slice for ZFS, you are responsible for making sure the partition table shows the partition type is ZFS. This can be done with OS X's built-in "gpt" command or the easier to use "gdisk" command, which can be downloaded [http://sourceforge.net/projects/gptfdisk/ here]. For detailed instructions, see [[Suppressing_the_annoying_pop-up|here]]. Partitions can also be made by resizing existing ones with '''diskutil'''.

== Creating a pool ==

Start using ZFS by first creating a storage pool with the command '''zpool'''. As mentioned above, the disk partition on which the pool will be created must be specified before creation.

Once the disk partition is decided, you may run the following command with a few preferred properties:
'''Recommended pool creation command line'''

sudo zpool create -f -o ashift=12 -O casesensitivity=insensitive -O normalization=formD $poolname mirror diskX diskY

Or using "\" to show it broken up over multiple lines:

sudo zpool create -f -o ashift=12 \
-O casesensitivity=insensitive \
-O normalization=formD \
$poolname mirror diskX diskY

* Replace $poolname with the name of the pool you want. For example, "tank."
* ''If you want to use the entire disk for ZFS'', replace diskX and diskY with the available disks. For example, disk1 and disk2.
* If you have already partitioned the disk, and wish to only use a slice, use diskXsN. For example, disk1s2.
* -f [https://openzfs.github.io/openzfs-docs/man/8/zpool-create.8.html Forces use of vdevs, '''even if''' they appear '''in use''' or specify a conflicting replication level. Not all devices can be overridden in this manner.] (not: "instructs ZFS to label the disk for you.")
* -o ashift=12 instructs ZFS to use 4K sectors, as described here: http://wiki.illumos.org/display/illumos/ZFS+and+Advanced+Format+disks

The default for ashift is 9, but you will most likely want to create pools with an ashift of 12, which is appropriate for 4096 (4k) disks (i.e., Advanced Format disks), even if your disks are still the older 512. If you are using SSDs in your pool now, or anticipate replacing any of your pool's disks with SSDs in the future, then an ashift of 13 is a better choice. It is important to get this right now because a vdev's ashift cannot be changed after the vdev is created.

On OS X you will want to use [http://en.wikipedia.org/wiki/Unicode_equivalence#Normal_forms NFD normalization], or quite a few applications won't work (e.g., iTunes). Read [https://towardsdatascience.com/what-on-earth-is-unicode-normalization-56c005c55ad0 What on Earth is Unicode Normalization?] helps understand why.

You can also decide to disable '''access time''', enable '''compression,''' and all those nice things. But that can be done at any time in ZFS. For example

sudo zfs set compression=lz4 $poolname

or for pool version 28 compatibility

sudo zfs set compression=on $poolname

If you do want compression, you should turn it on '''as soon as possible''', or enable it at the time the pool is created. Turning compression on later will ''only'' apply to new data added to a dataset going forward, ''not'' the preexisting uncompressed data you already put in the dataset while compression was turned off.

For example, you may want to use something like this

sudo zpool create -f -o ashift=12 -O compression=lz4 -O casesensitivity=insensitive -O atime=off -O normalization=formD tank mirror disk3 disk4

Or using "\" to show it broken up over multiple lines:
sudo zpool create -f -o ashift=12 \
-O compression=lz4 \
-O casesensitivity=insensitive \
-O atime=off \
-O normalization=formD \
tank mirror disk3 disk4

If you absolutely must be compatible with non-OpenZFS implementations of ZFS (e.g., Oracle Solaris), you'd need to do

sudo zpool create -f -o version=28 -o ashift=12 -O compression=on -O casesensitivity=insensitive -O atime=off -O normalization=formD tank mirror disk3 disk4

Or using "\" to show it broken up over multiple lines:

sudo zpool create -f -o version=28 -o ashift=12 \
-O compression=on \
-O casesensitivity=insensitive \
-O atime=off \
-O normalization=formD \
tank mirror disk3 disk4

For available properties to consider and set, see [https://docs.oracle.com/cd/E23824_01/html/821-1448/gazss.html#scrolltoc Introducing ZFS Properties].

== Unplugging a pool ==

The equivalent of unmounting a device before unplugging it is exporting a pool in ZFS terminology.

Before unplugging any devices you '''must export all pools using the device'''.

sudo zpool export $poolname

The export can sometimes fail if the mount is busy (as with all filesystems). So you might need to close any
applications still accessing the pool. Also, there is an option "-f" to force unmount while exporting:

sudo zpool export -f $poolname

If you are just rebooting, you do not need to export first.

== Feature flags ==
If you are creating a pool on another OpenZFS platform, and you want to make sure that pool is compatible with OpenZFS on OS X, you must not enable any [http://open-zfs.org/wiki/Features#Feature_Flags feature flags] not yet supported by OpenZFS on OS X.

For instance, let's say you were creating a pool using OmniOS, which currently supports more feature flags than OpenZFS on OS X.

To start out with all feature flags disabled, use the -d option when creating the pool:

sudo zpool create -d $poolname c2t1d0

To selectively enable only the feature flags supported by OpenZFS on OS X (as of 2014-08-01) use -d combined with -o feature@..., as follows:

sudo zpool create -d -o feature@async_destroy=enabled -o feature@empty_bpobj=enabled -o feature@lz4_compress=enabled $poolname c2t1d0

Or using "\" to show it broken up over multiple lines:
sudo zpool create -d \
-o feature@async_destroy=enabled \
-o feature@empty_bpobj=enabled \
-o feature@lz4_compress=enabled \
$poolname c2t1d0

And don't forget to specify the other options you want, as discussed above:
sudo zpool create -d \
-o feature@async_destroy=enabled \
-o feature@empty_bpobj=enabled \
-o feature@lz4_compress=enabled \
-O compression=lz4 \
-O casesensitivity=insensitive \
-O atime=off \
-O normalization=formD \
$poolname c2t1d0

(Note that illumos distributions such as OmniOS handle ashift indirectly as described here: http://wiki.illumos.org/display/illumos/ZFS+and+Advanced+Format+disks)