Lustre 2.0 Features

Lustre 2.0 and 2.x releases will introduce several significant new features and improved system functionality. This page provides descriptions of these features and lists the benefits offered by upgrading to the Lustre 2.0 release family. For the latest information on when Lustre 2.0 is expected to be released, see the Lustre Roadmap.

=Lustre 2.0.0=

The initial Lustre 2.0 release (known as 2.0.0) will offer these features:

Changelogs
Changelogs record events that change the filesystem namespace or file metadata. Events such as file creation, deletion, renaming, attribute changes, etc. are recorded with the target and parent file identifiers (FIDs), the name of the target, and a timestamp. These records can be used for a variety of purposes:


 * Record recent changes to feed into an archiving system.
 * Use changelog entries to exactly replicate changes in a filesystem mirror.
 * Set up "watch scripts" that take action on certain events or directories. Changelog record are persistent (on disk) until explicitly cleared by the user. The are guaranteed to accurately reflect on-disk changes in the event of a server failure.
 * Maintain a rough audit trail (file/directory changes with timestamps, but no user information).

These are sample changelog entries:

2 02MKDIR 4298396676 0x0 t=[0x200000405:0x15f9:0x0] p=[0x13:0x15e5a7a3:0x0] pics 3 01CREAT 4298402264 0x0 t=[0x200000405:0x15fa:0x0] p=[0x200000405:0x15f9:0x0] chloe.jpg 4 06UNLNK 4298404466 0x0 t=[0x200000405:0x15fa:0x0] p=[0x200000405:0x15f9:0x0] chloe.jpg 5 07RMDIR 4298405394 0x0 t=[0x200000405:0x15f9:0x0] p=[0x13:0x15e5a7a3:0x0] pics

The record types are:

FID-to-full-pathname and pathname-to-FID functions are also included to map target and parent FIDs into the filesystem namespace.

Why should I upgrade to Lustre 2.0.0 to get it?

Changelogs offer these benefits:


 * File/directory change notification
 * Event notification
 * Filesystem replication
 * File backup policy decisions
 * Audit trail

Additional Resources

For more information about changelogs, see:



Commit on Share
The Commit on Share (COS) feature detects conflicts by checking for uncommitted transactions from a different client before updating an object. The transaction commitment occurs first, then the update. Uncommitted transactions have no dependencies.

What this means is that if one client is doing some operation in memory (say creating a file dir/b) it can be sure that all of the stat required for dir to exist has already committed to disk, if it was created by another client. Dependent operations done by a single client can be asynchronous at the server, (e.g. doing an untar of a file from one client), and independent operations done by different clients (e.g. clients creating files in separate directories) can also be asynchronous, but if there are dependencies between different client operations then the dependent operations are synced to disk.

In conjunction with Version Based Recovery (introduced in 1.8) this allows clients to always be able to recover, regardless of whether other clients have failed.

Why should I upgrade to Lustre 2.0.0 to get it?

COS offers these benefits:


 * Better recovery with multiple node failures
 * Doesn't force fully synchronous operations

Additional Resources

For more information on COS, see:



Replication
The replication feature provides namespace and data replication to an external (remote) backup system without having to scan the file system for inode changes and modification times. Lustre metadata changelogs are used to record file system changes and determine which directory and file operations to execute on the replicated system. The replication feature differs from existing backup/replication/synchronization systems because it avoids full file system scans, which can be unreasonably time-consuming for very large file systems. Also, the replication process can be resumed from where it left off, so the replicated file system is fully synchronized when operation completes. Replication may be bi-directional for distinct directories.

The replicated system may be another Lustre file system or any other file system. The replica is an exact copy of the namespace of the original file system at a given point in time. However, the replicated file system is not a snapshot of the source file system in that its contents may differ from the original file system's contents. On the replicated file system, a file's contents will be the data in the file at the time the file transfer occurred.

Why should I upgrade to Lustre 2.0.0 to get it?

Replication offers these benefits:


 * Namespace-coherent duplication of large file systems without scanning the complete file system
 * Functionality is safe when run repeatedly or run after an aborted attempt
 * Synchronization facility to switch the role of source and target file systems
 * In the case of recovery, the feature provides for reverse replication

Additional Resources

For more information on replication, see:


 * Architecture Page - Replication
 * lreplicate man page

=Lustre 2.x=

Lustre 2.x releases will offer these features:

HSM
The HSM feature provides several mechanisms to interface with an external HSM system. External components include the policy engine, and file storage, retrieval, and removal methods. The external components are expected to run in userspace. Internal components include Lustre metadata extensions, and a distributed coordinator/agent architecture to call the file storage methods. Policy engine input and feedback is expected to occur primarily though the changelog. In its initial implementation, the HSM feature uses HPSS for the external components.

Why should I upgrade to Lustre 2.x to get it?

HSM offers these benefits:


 * Cost-effective filesystem expansion
 * Potential for backup policies in the policy engine

Additional Resources

For more information on HSM, see:



Clustered Metadata (CMD)
The CMD feature...

Why should I upgrade to Lustre 2.0.0 to get it?

Security CMD offers these benefits:



Additional Resources

For more information on CMD, see:



Security GSS
The Security GSS feature...

Why should I upgrade to Lustre 2.0.0 to get it?

Security GSS offers these benefits:



Additional Resources

For more information on Security GSS, see:



ZFS Object Storage Device (OSD)
The ZFS OSD feature...

Why should I upgrade to Lustre 2.0.0 to get it?

ZFS OSD offers these benefits:



Additional Resources

For more information on ZFS OSD, see: