[linux-lvm] What are they talking about?

[Kevin Corry]

(Once more - with feeling this time!)

Device-Mapper is the new kernel driver in 2.5. It replaced the LVM1 kernel 
driver from 2.4. This driver provides generic "volume management" 
capabilities. Specifically, it can create devices which simply redirect I/O 
to other underlying devices. Such a device could be thought of as a "logical 
volume".

LVM2 and EVMS are both actively developed projects that utilize the 
Device-Mapper driver for creating their "logical volumes". Neither LVM2 nor 
EVMS are (or will be) "in the kernel". All of the real complexity of volume 
management is done in user-space. It is far more sensible to ask a question 
like "will LVM2 and/or EVMS be included in the next release of Red Hat or 
Debian?" And the next major release of these distros may not correspond 
exactly with the release of the 2.6.0 kernel.

To prevent reposting all of the gory details, please see a very similar 
previous discussion at:
http://marc.theaimsgroup.com/?t=104164610600002&r=1&w=2
and
http://marc.theaimsgroup.com/?t=104195031700002&r=1&w=2


On Wednesday 21 May 2003 12:42, Anastasios A. Papadopoulos \(Tas\) wrote:
> Now I am really confused.  (Sorry folks, it doesn't take much).
>
> I thought that EVMS was dead.  The EVMS web site says something to the
> effect that the new EVMS product will be mostly a front end for (LVM?).  Am
> I reading that wrong?
>
> Also in their announcement, the EVMS development group said that Linus etal
> decided to include LVM but not EVMS.
>
> Can someone straighten me out, please?
>
> Thanks
>
> ----- Original Message -----
> From: "Greg Freemyer" <freemyer at NorcrossGroup.com>
> To: "LVM Mailing list" <linux-lvm at sistina.com>
> Sent: Wednesday, May 21, 2003 1:06 PM
> Subject: [linux-lvm] What are they talking about?
>
>
> In the article at http://www.eweek.com/article2/0,3959,1054003,00.asp
>
> they talk about the 2.6 kernel having a DM, but not a LVM.
>
> What are they trying to say?  What is it they think is missing?
>
> === Quote from the article
>
> According to Witham, a number of features that the development community
> believes are not yet ready to be incorporated into the 2.6 kernel may very
> well be pushed to 2.7.
>
> Among these features are support for complete Non-Uniform Memory Access
> as well as an EVMS (Enterprise Volume Management System), which deals
> with the difficult and controversial issue of volume management, Frye said,
> adding that 2.6 would be better than 2.4 in terms of volume management even
> without the EVMS.
>
> Oracle Corp. and Red Hat Inc. officials have also previously called for
> volume
> management. Wim Coekaerts, principal member of Oracle's technical staff, in
> Redwood Shores, Calif., said: "We would like Linux to have a Logical Volume
> Manager. The 2.6 kernel will have a device manager, but we need an LVM."
>
> Paul Cornier, executive vice president of Red Hat, in Raleigh, N.C.,
> agreed.
>
> "Making a more generic cluster file system is important to us, as is an
> industrial-strength Logical Volume Manager," Cornier said. "A distributed
> lock
> manager completes things. This is functionality that needs to go into the
> operating
> system but is unlikely to be found in the next [kernel] upgrade."
>
> IBM's Frye said that there's clearly a need for an improved volume
> management
> system and that Linux is not yet good enough in that regard.
> ====
>
> Thanks
> Greg
> --
> Greg Freemyer

-- 
Kevin Corry
kevcorry at us.ibm.com
http://evms.sourceforge.net/