[Evms-announce] Re: [Evms-devel] EVMS scrapped

[Kevin C. <co...@us...>]

On Tuesday 07 January 2003 08:15, Stephen Arden wrote:
> All,
>
> Please excuse me while I get this out of my system.
>
> I am relatively new on this list as we test and contemplate using EVMS on
> Linux on xSeries and zSeries systems and all
> this information and mis-information about EVMS being scrapped isn't
> helping anyone make a decision.
> It is also starting to show up on other Linux forums I am on.
> From what I have read I think I understand that all we're talking about is
> a move to user-level code and out of the kernel, or at least that a
> standard
> kernel feature will be used as an interface. That's fine, but it doesn't
> seem to be stopping rumors and mis-information from spreading.
>
> If EVMS is to continue on and live to a ripe old age, it would be nice is
> someone (someone high enough up in the food chain so that their statements
> carry sufficient weight)  would issue a "definitive" statement about EVMS
> plans so we can all put this issue to bed.

Ok, once more, for the record: EVMS is *NOT* going away.

There are several developers here who's sole job this year is to develop 
EVMS. We are continuing to improve the code and add new features. Just last 
week we released the first package of the new EVMS design. For those who 
missed the announcement, please take a look at:
http://marc.theaimsgroup.com/?l=evms-devel&m=104136990521938&w=2
New features that will be coming this month include HA clustering support and 
volume "move" capabilities.

The article mentioned on this list the other day 
(http://news.com.com/2100-1001-979142.html?tag=fd_top) is certainly 
misleading. The main distinction that many people don't seem to understand is 
the difference between the kernel device driver and the user-space volume 
management tools. EVMS is a set of user-space administration tools. LVM2 is 
also a set of user-space administration tools. Device-mapper is a kernel 
device driver which is used by both EVMS and LVM2. It was not LVM2, but 
Device-mapper, that was accepted into the 2.5 kernel.

Previously, EVMS had its own kernel device driver. When Device-mapper was 
accepted into the 2.5 kernel, we decided it would be far simpler in the long 
run to adjust our user-space tools to work with that driver instead of the 
driver we had been using. The main affect of that decision is that volume 
discovery is now performed in user-space instead of directly in the kernel. 
This is an affect that most users will barely notice. Users who look at the 
old EVMS and the new EVMS will see almost no difference in how it operates 
and how various volume management tasks are performed.

As for the article's statement that we "would scrap much of [the] project", 
this is also misleading. Since we switched kernel drivers, we did drop *some* 
of the code we had been developing. This dropped code does not account for 
any more than about 20% of the total code we had developed. And this number 
is also somewhat incorrect, since we have been able to take some of the work 
from our old kernel driver and use it to write some additional plugins for 
Device-mapper. So in reality, a minor amount of code has been "scrapped". 
This is the normal course of evolution for *any* software project. As new 
ideas are formed and new directions taken, old code is discarded and new code 
is written.

As I said above, we are continuing to actively develop EVMS. We are also 
working with the LVM developers to shake out any remaining issues with 
Device-mapper. In my opinion, it is looking to be a very solid, reliable 
kernel driver which both projects will be able to build on.

Stephen, feel free to pass this note along to the other forums/lists you 
mentioned above. Or let me know the lists in question and I will respond 
there as well.

If anyone has any other concerns or questions about EVMS, please email this 
list, email me directly, or drop by our IRC channel (irc.freenode.net, 
#evms). I will be happy to discuss any issues you think have not been 
addressed.

-- 
Kevin Corry
co...@us...
http://evms.sourceforge.net/