[Debian-ha-maintainers] Linux-HA Jessie release goals

[Martin Gerhard Loschwitz]

Folks,

with Wheezy being done, it's a good point in time now to discuss the release goals for the
Linux-HA stack in Jessie. Right now, we have Pacemaker 1.1.9 along with its dependen-
cies in Experimental (including Corosync 2), uploading this to Unstable is the next logical
step. According to Pacemaker's upstream Andrew Beekhof, Pacemaker 1.1.9 continues to
work with Corosync 1.x, so backporting Pacemaker afterwards should not be too big of an
issue either.

1.However, please keep in mind that the cluster stack has been a moving target lately with
things changing on a regular base. According to, again, Andrew Beekhof, distributions
should take the approach that Red Hat will take for its RHEL 7 distribution, documented as
option 3 here:

http://theclusterguy.clusterlabs.org/post/34604901720/pacemaker-and-cluster-filesystems

I am very much all in for that because it allows us to get rid of redhat-cluster (including all
the things like cman and rgmanager) and means a lot of work less. The negative side is
we would effectively be losing support for OCFS2+Pacemaker (and probably we would be
losing support for cLVMd+Pacemaker, too, unless someone patches it to support Corosync
2.0, of course). 

2. Another issue is Heartbeat support. Andres Rodriguez has brought up the idea of drop-
ping support for the Heartbeat communication stack altogether to force a migration to the
new Corosync 2. While I was originally reluctant to this, by now I think there are quite some
reasons speaking for it.

There has not been a single Heartbeat release for almost two years now, according to
Philipp Marek from LINBIT, Heartbeat's current upstream, a new version 3.0.6 is planned:

2013-05-19 #linux-ha at Freenode
(09:33:54) <flip214> Madkiss: there'll be a heartbeat 3.0.6 in the near future…

However, there were no commits to Heartbeat's Mercurial repository either, so I have no
idea what it will deliver. Thing is: If we plan to keep Heartbeat support in Pacemaker even
for Jessie, that would refer to a timeframe of 5-6 years from now on, because if Ubuntu 
14.04 LTS has HB support (and we plan to keep the packages in Sync as far as possible), 
we need to support it until 2019. Which, if I am honest, scares  me a bit. Plus, we have no 
idea if upstream, at some point, will simply decide to drop the Heartbeat support altogether 
(Andrew, your input would be highly appreciated on this one).

3. We will, however, need to provide some sort of upgrade path for this. People running a
cluster with Pacemaker as plugin at the moment will blow up their setup by updating to
Pacemaker 1.1.9+Corosync 2 because that does not support the plugin stuff anymore, and
Pacemaker will lose the plugin RSN anyway, according to Andrew. The same goes for the
DLM mess; people running Pacemaker+CMAN (or even those on Squeeze running Pace-
maker with the old control daemons) will blow their setups up irreparably, in fact, switching
to option 3 in the aforementioned document means effectively removing support for cLVMd
from Debian (OCFS2 can still work as it has its own clustering mode).

4. Last but not least, there's the cluster control shell thing. We need to decide is which shell 
we will be supporting. crmsh is packaged for Debian and in the archive already; my first 
attempt to package PCS was rejected by Luca Falavigna last week, I am preparing an 
updated build. However, packaging PCS is a bit hairy for numerous reasons, one being the 
fact that pcsd, the tool's internal daemon, requires ruby gems which are non packaged at the 
moment. I took the liberty to create some preliminary packages of these ruby gems and will 
be asking the Debian ruby people to give me a helping hand on this one.

It looks like PCS will soon be merged into Pacemaker anyway, or at least that is what I hear.
Andrew, could you comment on this one? Thanks in advance!

Given that still 98% of all examples out in the intarwebs use the "crm" command, which is the
crmsh, and given that crmsh has proven to be useful and usable lately, I would prefer to keep
both packages (or keep crmsh if PCS becomes part of Pacemaker anyway)

Summary: I opt for 
a. Removing support for Heartbeat from Pacemaker
b. Switching to Pacemaker 1.1.9 or later + Corosync 2
c. Providing DebConf notices about people breaking their setups
d. Continue to support crmsh  alongside with PCS

Any comments are highly appreciated.

Best regards
Martin

-- 
Martin Gerhard Loschwitz
Chief Brand Officer, Principal Consultant
hastexo Professional Services
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 841 bytes
Desc: Message signed with OpenPGP using GPGMail
URL: <http://lists.alioth.debian.org/pipermail/debian-ha-maintainers/attachments/20130519/a5141e25/attachment.pgp>