[Linux-cluster] new userland cman

[Patrick Caulfield]

This has got to the stage where I'd be grateful for any testing other people can
 do, though obviously don't endanger a production system!

You should be able to run the DLM and GFS on this, see

https://www.redhat.com/archives/linux-cluster/2005-September/msg00177.html

for (very) brief instructions. There is a new clvm patch available in the
cluster CVS at cman/lib/clvmd-libcman.diff

Here's a list of the user-visible changes, please feel free to ask questions on
the list.

good
----
- (optional) encryption & authentication of communications
- Multiple interface support (unfinished, needs AIS and cman work)
- Automatic re-reading of CCS if a new node joins with an updated config file

bad
---
- Always uses CCS (cman_tool join -X removed)*
- Compulsory static node IDs (easily enforced by GUI or command-line)
- Can't have multiple clusters using the same port number unless they use a
different encryption key. Currently cluster name is ignored.**
- Hard limit to size of cluster (set at compile time to 32 currently)***

neutral
-------
- Always uses multicast (no broadcast). A default multicast address is supplied
if none is given
- libcman is the only API ( a compatible libcman is available for the kernel
version)
- Simplified CCS schema, but will read old one if it has nodeids in it.****

internal
--------
- Usable messaging API
- Robust membership algorithm
- Community involvement, multiple developers.


* I very much doubt that anyone will notice apart from maybe Dave & me

** Could fix this in AIS, but I'm not sure the patch would be popular upstream.
It's much more efficient to run them on different ports or multicast addresses
anyway. Incidentally: DON'T run an encrypted and a non-encrypted cluster on the
same port & multicast address (not that you would!) - the non-encrypted ones
will crash.

*** I doubt that the old cman worked well above 30 nodes anyway. I intend to do
some AIS hacking to improve this situation by drastically reducing the network
packet size.

**** The main difference here is that the multicast address need only be
specified once, in the <cman> section of cluster.conf. The interface used will
be the one that is bound to the hostname mentioned.


patrick

-- 

patrick