[Linux-cluster] RFC: updating cluster.conf

[Lon Hohberger]

On Mon, 2008-06-23 at 11:16 -0500, David Teigland wrote:

> 1. How often do you update cluster.conf?  ("Never" would be valuable
>    feedback.)

Varies.  During development / testing, several (10-20) times a day,
otherwise, rarely.  One cluster's config version is in the 300s, singly
incremented; another is in the 400s, but we skipped 100 on that one ;)


> 2. What changes do you make?  e.g. add nodes, change fencing settings,
>    add or change rgmanager settings.

Mostly rgmanager and qdiskd settings.

> 3. How do you currently update cluster.conf?  Cluster online or offline?
>    Manually scp to all nodes?  ccs_tool?  conga?  What do you like and not
>    like about the method you use now?

Typically - 
  edit on one node with vim.
  ccs_tool update /etc/cluster/cluster.conf
  cman_tool version -r <new_config_version>

> 4. How would you like to do updates to cluster.conf in the future?
>    Conga (graphical management interface)?  Command line program that
>    updates /etc/cluster/cluster.conf on all cluster nodes?
>    Manually scp to all nodes?  Other?

Something similar, except sans the "cman_tool version -r" part.

I suppose one could envision something using inotify so that upgrading
was fully automatic based on timestamps (eliminating the need for the
config serial #), but there are things to think about there (e.g. if
dates aren't in sync across the cluster...).  There's a reason BIND uses
serial numbers contained within its individual zone/config files...


> 5. Would you like to use an LDAP server?  All cluster nodes would read
>    cluster.conf info from the server; updates would just be made on
>    the server.

Truthfully, I will probably not use it much. :)

One thing that I would really disagree with: given a running a cluster,
forcing an administrator to manually distribute the configuration.  That
said, we might be able to push this back on ricci instead of using the
distribution code as it exists in ccsd today.

-- Lon