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Re: [Evms-devel] [ANNOUNCE] EVMS Release 1.1.0-pre4

On Sat, Jul 06, 2002 at 02:15:11PM -0500, Steve Greenland wrote:

> On 06-Jul-02, 13:30 (CDT), Matt Zimmerman <mdz@debian.org> wrote: 
> > Debian packages for EVMS 1.1.0-pre4 are now prepared for Debian
> > experimental, and should be available from the mirrors tomorrow.
> > 
> > The impatient can get them here:
> > 
> > deb http://people.debian.org/~mdz/evms ./
> > deb-src http://people.debian.org/~mdz/evms ./
> > 
> > I have tested these packages on my system and they work for me, but that is
> > all that I can say at this time.  If you try these packages, let me know how
> > they work for you.
> All of which reminds me...can/would somebody explain the
> difference/relationship between (LVM/LVM2) and EVMS? Or point me at the
> appropriate URL? Based on the EVMS site, it seems that EVMS is not a
> volume manager per-se, but provides an API to various VM-type services.
> Is that correct?

More or less.  I have zero experience with LVM2, so I'm no help there, but
compared to LVM version 1, EVMS takes a more holistic approach to volume
management.  It handles everything from raw disks, through partitions,
logical volume management, snapshotting, and even filesystem creation and
resizing.  These operations are managed by plugins, so EVMS has:

- Several so-called segment manager implementations, which handle things
  like DOS partition tables, GPT, etc.

- Several volume manager implementations (an LVM-compatible one, an
  AIX-compatible one, and an OS/2 compatible one), with all the usual
- Its own RAID (0,1,5) implementation based on the kernel md driver

- So-called "feature object" plugins which do things like bad block
  relocation, snapshotting and raw disk concatenation

- Filesystem interface modules (FSIM) plugins for ext2/3, jfs, reiserfs, and
  swap (so far), which make use of the standard libraries and tools for
  their respective filesystems and present a standard API for creation,
  resizing, consistency checking, etc.

each of these integrated at their own layer, and stacked on top of one
another in order to form a complete volume management framework.  It is
split into userspace (engine) and a kernel-space (runtime) parts, and the
userspace bits provide a unified volume management API for which several
frontends exist (command-line, ncurses, GTK, etc.).

So basically, you can fire up the EVMS GUI on a bunch of brand-new disks,
and by the time you close it, you can have a set of fully partitioned,
RAIDed, logical-volumed, snapshotted block devices with filesystems on them,
which can be created, destroyed, resized, etc. from the same interface, and
also programmatically manipulated via another interface or a C API.

And there is more good stuff in the pipeline.  The EVMS team has been
extremely responsive and helpful over the past 8 months as I have developed
and maintained these packages, and I'm sure that they would be glad to
answer any questions you have on the evms-devel@lists.sourceforge.net list.

 - mdz

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