[Ocfs2-announce] OCFS2 1.4 *BETA* Announcement

[Sunil Mushran]

All,

We are pleased to announce the release of OCFS2 1.4 *BETA*. We are currently
targeting production with the SLES10 SP2 and RHEL5 U2 releases, both of 
which
are currently in BETA. OCFS2 1.4 *BETA* has been shipping with SLES10 SP2
BETA for sometime now. This announcement provides packages for the same for
the RHEL5 U2 BETA release.

While this is a BETA release and it is not advisable to deploy it in a
production environment, we would like to encourage you to use it in your 
test
cluster and provide us with constructive feedback.

Before deploying, all users are encouraged to read the README in its 
entirety,
especially the sections on the compatibilities and the new filesystem 
defaults.

The packages for OCFS2 1.3.9-0.1 *BETA* for RHEL5 U2 BETA are available 
here:
http://oss.oracle.com/projects/ocfs2/files/RedHat/RHEL5_BETA/

The packages for OCFS2-TOOLS 1.3.9-0.1 *BETA* for RHEL5 are available here:
http://oss.oracle.com/projects/ocfs2-tools/files/RedHat/RHEL5/i386/beta/
http://oss.oracle.com/projects/ocfs2-tools/files/RedHat/RHEL5/x86_64/beta/

As always, we look forward to hearing from you on the 
ocfs2-users at oss.oracle.com
mailing list.

The OCFS2 Team

OCFS2: http://oss.oracle.com/projects/ocfs2
TOOLS: http://oss.oracle.com/projects/ocfs2-tools


README
============================================================================

WHAT'S NEW

This release makes available the features that have been steadily 
accumulating
in the mainline Linux kernel tree over the past 18 months or so. The list of
features added since the 1.2 release is as follows:

* File Attribute Support
* Directory Readahead
* Performance Enhancement - stat(2)
* Performance Enhancement - unlink(2)
* Splice IO (support to be enabled by release)
* Atime/Mtime Updates
* Sparse File Support (ondisk change)
* Unwritten Extents/Punch Holes (ondisk change, support via ioctl only)
* Shared Writeable mmap(2)
* Data in Inode (ondisk change, tools support expected by release)
* Online Filesystem Resize
* Clustered flock(2)
* Ordered Journal Mode

For the full description, please refer to the following link:
http://oss.oracle.com/projects/ocfs2/dist/documentation/ocfs2-new-features.html#FEATURES


FILESYSTEM COMPATIBILITY

OCFS2 1.2 is fully ondisk compatible with OCFS2 1.4. Users installing this
release will be able to mount their existing volumes as-is.

However, one will not be able to do a rolling upgrade to 1.4 as the network
protocol has changed.

Also, users mounting existing volumes will not have access to all the new
features. Features entailing ondisk changes, like Sparse Files, Unwritten
Extents and Data-in-Inode, will need to be explicitly enabled using 
tunefs.ocfs2.
Once enabled, the same volumes can still be mounted using the older 1.2 
software,
but only after the said feature is disabled.


TOOLS COMPATIBILITY

Simply put, the latest OCFS2-TOOLS always support all existing versions 
of the
file system. While users looking to upgrade to 1.4 (or to the latest 
Linux kernel),
must install OCFS2-TOOLS 1.4, existing 1.2 users can do so at their own 
convenience.


NEW FILESYSTEM DEFAULTS

Sparse file support is activated by default for volumes formatted using 
the new
mkfs.ocfs2. Users wishing to retain full compatibility with OCFS2 1.2 should
specify "--fs-feature-level=max-compat" during format.

The other change in the defaults concerns the journaling mode. While 
OCFS2 1.2
supported the writeback data journaling mode, 1.4 not only adds support 
for the
ordered data journaling mode, it also makes it the default. Users wishing to
keep using the writeback mode can enable it by mounting the volume using the
data=writeback mount option.

The difference between the two modes is that in the ordered mode, the 
file system
flushes the file data to disk before committing the metadata changes. In 
writeback,
no such write ordering is preserved.

While the writeback mode guarantees internal filesystem integrity alongwith
better overall throughput than the ordered mode, there exists a 
possibility of
stale data appearing in files after a crash and a journal recovery.


DISTRIBUTIONS

OCFS2 1.4 is a backport of the filesystem in the mainline Linux kernel tree,
2.6.25-rc6. It has been backported to work only on the 2.6.16 (SLES10) 
and the
2.6.18 (RHEL5) kernels. No attempt has been made to ensure that it even 
builds
on the other kernels.

Users using a different distribution are encouraged to use the filesystem
shipped with that distribution and not attempt to build OCFS2 1.4 on it. 
There
is no reason to do so as 1.4 is simply a backport of the version in the 
mainline
tree and has very little difference in functionality with it. Please 
note that
as a rule, we apply bug fixes to all relevant kernel trees and not just the
enterprise kernels.


FEEDBACK

The one known missing piece in this release is CDSL support. Our 
implementation
in the 1.2 release was not accepted by the Linux kernel community. While 
we can
always merge back the support for only the 1.4 release, we are aiming to 
make
1.4 release look as much as possible like mainline so as to make it 
easier for
users to move between kernels/distributions.

With that in mind, we are looking for feedback concerning the use of 
CDSL. As in,
are you using CDSL? If so, how many files? Which type of files? Answers 
to the
same will help us decide our approach to the solution.


WHAT'S MISSING

Apart from CDSL support, we still need to add tools support for 
data-in-inode,
enable splice io and update the documentation.


FUTURE PLANS

While not set in stone, the list of "major" features that we are/will be 
working
on looks something as follows:

1. Framework for Integrating with Userspace Clusterstack(s)
   This will allow OCFS2 to work with different userspace cluster stacks.
   We are aiming to to push changes for the same in the upcoming 2.6.26 
kernel.

2. CMAN Integration
   In the coming months, the open source cluster stacks as distributed 
by Red Hat
   and SUSE, are likely to somewhat merge into a new CMAN that is 
layered atop
   OpenAIS. We will use the above framework to integrate OCFS2 with the 
new CMAN.
   Please note that we will continue to support the "classic" O2CB 
cluster stack
   and make the choice of cluster stack user configurable. For more 
information,
   please refer to this link.
   http://sources.redhat.com/cluster/wiki/HomePage

3. Extended Attributes
   This feature is currently in development. Once it is committed into
   the mainline tree, we will we decide whether to backport it to 1.4 or
   wait for SLES11 / (RH)EL6 to make it available on Enterprise 
distributions.

4. POSIX Locking
   While we managed to add support for clustered flock(2) (aka BSD locking)
   in 2.6.25, we are still looking to add support for its POSIX cousin.

5. Online Adding of Node-Slots
   This will allow users to increase the number of node-slots without 
having to
   umount the volume on all nodes. (Number of node slots dictates the number
   of nodes that can mount the volume concurrently.)

6. Online Defragmentation
   This will make the file system coalesce file data extents in order to 
boost
   performance.

7. Indexed Directories
   This will offer better performance during lookups in directories 
having more
   than 10,000 files.

8. JBD2 Support
   This will allow users to increase the volume sizes to 4PB. We will 
take on
   this task after ext4/jbd2 code base has somewhat stabilized.
==============================================================================