ZFS Filesystem bindings for Ruby¶ ↑

LibZfs Ruby is a C library interface to ZFS, Sun’s Zettabyte File System, which made its debut in OpenSolaris. Actually, Solaris 10 stable release, Open Solaris and FreeBSD-8.0 provide stable implementations.

There is also a community driven implementation for Mac OsX, but haven’t tried to get this library running there yet.

A Word of Caution¶ ↑

At this moment, I’m trying to review and test this library into as many as possible different versions of Open Solaris. The library hasn’t been updated since 2007 so, it’s perfectly possible to find bugs and, what is worse, cause infamous Segmentation faults.

Building¶ ↑

rake compile

Usage¶ ↑

Previous version have some code intended to manage ZFS Storage Pools creation/deletion. However, getting that code working is not too high on the priority list; there are other interesting functionalities provided by the ZFS library which should be implemented before, like zfs send/recv, since it looks like those would be widely used if you compare with Zpool creation.

The idea is to progressively provide a ruby interface for the most frequently used subcommands of the zfs and zpool command line utilities.

ZFS Storage Pools.¶ ↑

The library provides equivalents for the following zpool subcommands:

zpool list
zpool get property pool
zpool set property=value pool
zpool status pool

Primary usage of the Zpool class might be iteration over the different storage pools defined on the system:

[@zlib = LibZfs.new]
Zpool.each [(@zlib)] do |zpool|
  # access to each zpool instance
end

One can, anyway, access directly to a given Zpool using its name, either as a String or a Ruby Symbol:

[@zlib = LibZfs.new]
# Use a String:
@zpool = Zpool.new('pool_name' [, @zlib])
# Use a Symbol:
@zpool = Zpool.new(:pool_name [, @zlib])

Then, for a given Zpool instance, we can access to any defined property using @zpool.get('propname') or set any property by using @zpool.get('propname', 'propval').

Of course, any attempt to set an invalid value for a property, or trying to set any value for a read-only property will result in an error. (See LibZfs error methods in order to get more info).

Finally, status method will return the current Zpool instance status as any of the constants defined at ZfsConsts::State::Pool.

ZFS Datasets¶ ↑

The library provides equivalents for the following zfs subcommands:

zfs list
zfs get property dataset/name
zfs set property=value dataset/name
zfs destroy dataset/name
zfs snapshot dataset/name@snap
zfs rollback dataset/name@snap
zfs mount dataset/name
zfs unmount dataset/name
zfs clone dataset/name@snap another/dataset
zfs promote another/dataset
zfs rename dataset/name another/name
zfs share dataset/name
zfs unshare dataset/name

We can also iterate over root filesystems using ZFS.each:

[@zlib = LibZfs.new]
ZFS.each [(@zlib)] do |zfs|
  # access to each root filesystem zfs instance
end

We can say these root filesystems will be the equivalent for the system defined Zpools. Then, for these and any other dataset, we can use one of the different iteration methods:

zfs.each_filesystem
zfs.each_snapshot
zfs.each_dependent

While it’s obvious the type of datasets each_filesystem and each_snapshot will iterate over, it’s convenient to highlight that each_dependent will iterate not only over snapshots and children filesystems for the current ZFS instance, but also over any associated clone.

For ZFS Datasets is also possible to access directly to any of them instantiating the ZFS class with the dataset name and type:

[@zlib = LibZfs.new]
# Use a String:
@zfs = ZFS.new('dataset/name', ZfsConsts::Types::FILESYSTEM [, @zlib])

Run the test suite:¶ ↑

In order to be able to run the test suite, need to create some predefined ZFS Datasets and Storage Pools:

sudo mkdir /export/vdev
sudo mkfile 128m /export/vdev/d1
sudo zpool create tpool /export/vdev/d1
sudo zfs create tpool/home
sudo zfs create tpool/thome
sudo zfs snapshot tpool/thome@snap
sudo zfs clone tpool/thome@snap tpool/thomeclone
sudo zfs set zfs_rb:sample=test tpool/thome
sudo zfs create tpool/rollback

Then, you need to run the tests as root with:

sudo rake test

or, you need to run it with a privileged user with all the required profiles, including:

ZFS File System Management
ZFS Storage Management
File System Management
SMB Management

by running:

pfexec rake test

Tested Systems¶ ↑

I’ve successfully built and tested the library on the following Open Solaris Versions:

• Open Solaris 2009.06 (snv_111b)

• Solaris Nevada 2010.02 Preview (snv_117)

• Open Solaris Development 134 (snv_134)

It’s also properly building on FreeBSD 8.0.

TODO:¶ ↑

• Review arguments given to all the C library functions, perform the appropriated type checks, and raise ArgumentError when proceeds.

• Validate Zpool/ZFS properties given to @zfs.set, @zfs.get, @zpool.get, @zpool.set.

• Allow @zfs.set to use numerical values too.

• Handle properties of type Integer from @zfs.get_user_prop

• Implement the equivalents for the following zfs subcommands:

  zfs send
  zfs receive
  zfs release
  zfs hold
  

• Some refactoring: zetta_fs_dataset_exists, zetta_fs_create and zetta_fs_new share a lot of code which could be using the same C function.