Date: Thu, 23 Dec 1999 16:56:54 -0700 (MST)
From: "Peter J. Braam" <braam@cs.cmu.edu>
To: linux-fsdevel@vger.rutgers.edu, linux-kernel@vger.rutgers.edu,
Subject: Object Based Storage and File System Snapshots: alpha release

Object based storage & File System Snapshots: alpha release
-----------------------------------------------------------

Stelias Computing is pleased to announce the first public release of
its object based storage software.  At this time we are releasing a
driver and a file system which together access Ext2 formatted disks,
and a module for file system snapshots.  This is alpha quality, kernel
software, for use with Linux 2.3.31 kernels.  Please exercise
caution. It is Open Source, runs on Linux only at this time and can be
obtained from http://www.lustre.org.

Object based storage breaks with the block device paradigm and
instroduces "smart" drives that handle objects like inodes. We expect
that our work as well as that of others in this arena, will lead to a
suite of advanced storage management software and to a new cluster
file system.  The cluster file system is named the Lustre file system
(Linux CLUSTRE), and will be forthcoming during the next year. 

We have built a simulated object based disk, using Ext2 disk format.
To exploit such drives, a file system is the most obvious choice.  An
object based file system that writes directories in Ext2 format is
included.  When used with the Ext2 object based disk driver, it
reads/writes Ext2 file systems and fsck is available for recovery. Our
file system has been used with other object based disk drivers - as
long as the protocol is correctly implemented it should work.

The power of this architecture lies in the fact that modules can be
placed between the file system and the object based driver. For
example, modules for aggregation (RAID), file system snapshots,
hierarchical storage management, encryption/compression find a natural
place between the file system and object based storage driver.  We
expect to release more modules in the future, but at this time an
experimental driver is included that can make snapshots (read only
clones) of Ext2 file systems.  There is a utility that can delete
snapshots and change a file system back to the state of a historical
snapshot.  The snapshot architecture found here is very different from
bot the Network Appliances approach and the AFS/Coda approach.

Please tell us what you think of this project, and of your experiences
with the software - you might be able to influence further work.  If
you want to contribute to this software, please contact us so that we
can tell you where we are heading.  We expect to release more software
frequently now - subscribe to the obd-announce mailing list if you
want to be informed.

Stelias wishes to thank many for support, advice and stimulating
discussions on this topic.

Peter J. Braam  -     braam@stelias.com / braam@cs.cmu.edu
Michael J. Callahan - mjc@stelias.com 
Andreas Dilger  -     adilger@stelias.com

Stelias Computing Inc.