[cdwg] Lustre 2.6.0 released

[Jones, Peter A]

We are pleased to announce that the Lustre 2.6.0 Release has been declared GA and is available for download<https://downloads.hpdd.intel.com/public/lustre/latest-feature-release/> . You can also grab the source from git<http://git.whamcloud.com/fs/lustre-release.git/commit/73ea776053d99f74a9f5679fe55ec5d9461b8a89>

This major release includes new features:

MDT-OST Consistency Check and Repair (LFSCK Phase 2)- Allows the MDS to verify the consistency of a Lustre filesystem while it is mounted and in use. The latest enhancements are to check and repair the validity of OST objects of regular files and to identify and optionally remove or link into lost+found OST objects that are not referenced by any files on the MDS. This development is funded by OpenSFS (LU-1267<https://jira.hpdd.intel.com/browse/LU-1267>)
Single Client Performance Improvements – Single thread per process IO performance has been improved. This work was discussed in details at LUG<http://cdn.opensfs.org/wp-content/uploads/2014/04/D1_S6_LustreClientIOPerformanceImprovements.pdf>  (LU-3321<https://jira.hpdd.intel.com/browse/LU-3321>)

Striped Directories -Enables a single directory to be striped across multiple MDTs to improve single directory performance and scalability. This is a technology preview of part of the DNE phase 2 work funded by OpenSFS that will be fully available in a future Lustre release (LU-3531<https://jira.hpdd.intel.com/browse/LU-3531>)

Fuller details can be found in the change log<https://wiki.hpdd.intel.com/display/PUB/Changelog+2.6>, the scope statement<https://wiki.hpdd.intel.com/display/PUB/Lustre+2.6+Scope+Statement> <https://wiki.hpdd.intel.com/display/PUB/Lustre+2.6+Scope+Statement> and the test mat<https://wiki.hpdd.intel.com/display/PUB/Lustre+2.6>rix<https://wiki.hpdd.intel.com/display/PUB/Lustre+2.6>
The following are known issues in the Lustre 2.6 Release:

LU-5057<https://jira.hpdd.intel.com/browse/LU-5057> - A rare race condition can lead to an LASSERT when unmounting an OST.
LU-5150 <https://jira.hpdd.intel.com/browse/LU-5150>  - Empty access control lists (ACLs) will be stored for copied files when using a ZFS MDS. It does not affect ldiskfs MDSes.
LU-4367 -<https://jira.hpdd.intel.com/browse/LU-4367> Metadata performance is affected for unlinking files in a single shared directory in a manner common with mdtest benchmark pattern.
LU-5420<https://jira.hpdd.intel.com/browse/LU-5420> - DNE configurations with multiple MDTs sharing a single node with an MGS may hang during MDT mount or fail to mount an MDT after unclean shutdown.
Work is in progress for these issues.

NOTE: Users should note that usage of the e2fsprogs-based lfsck has been deprecated and replaced by "lctl lfsck_start”. Using older e2fsprogs-based lfsck may lead to filesystem corruption. Once available, it is also recommended to use e2fsprogs-1.42.11.wc2 (or newer).
Please log any issues found in the issue tracking system<https://jira.hpdd.intel.com/>

We would like to thank OpenSFS<http://www.opensfs.org/>, for their contributions towards the cost of the release and also to all Lustre community members who have contributed to the release with code and/or testing.