[Linux-cluster] Cluster name vs. alias in cluster.conf

[James Parsons]

Jos Vos wrote:

>Hi,
>
>Since system-config-cluster-1.0.27, the "name" attribute in the "cluster"
>node always stays "alpha_cluster" (when editting a new config with the
>GUI) and only the "alias" attribute is set to the name of the cluster
>specified in the GUI.
>
>Is this a feature or a bug?  Someone also told me that this causes
>problems with the locktable names of GFS filesystems, because the
>cluster's name (not the alias) is used as part of the locktable name.
>
>  
>
Great question, Jos.

First of all, the alias attribute for cluster name was added for two 
reasons:
1) First, we started building some tools that made cluster creation 
easier and automated alot of the drudgery. We felt (perhaps incorrectly) 
that the true name of the cluster was probably something most users did 
not care about, so we began using generated alphanumeric strings to name 
clusters and make two clusters created with the deployment tools very 
unlikely, as two clusters with the same name on the same subnet would be 
a very bad thing. So that an administrator could name the clusters 
something convenient to remember what they were (file system, web 
sertvices, etc.) and because of #2 below, we introduced an attribute 
that would only be used by the UI.

2) After a cluster is up and running, changing the name of a cluster 
requires shutting down the cluster and reconfiguring it. If a running 
cluster's purpose were to change, it might be convenient to be able to 
rename it in the UI without having to pull your databases offline for 
such a minor procedure. I guess you would have to change the properties 
on GFS as well, if you were using it. I am not sure if you can do that 
very easily offhand...but it seems a shame to have to remake your FS 
just because you want to call the cluster "Production CNC Services - 
Dept. 1471" one day, instead of "Cluster1"...so this is not meant to be 
smarmy - but rather explain the intended use case for this feature.

So, this is why the alias for cluster name was introduced. Recently I 
was made aware that admins were using the alias'd name of the cluster as 
an arg to mkfs_gfs (or whatever the gfs creation utility is called - i 
forget right now :) and of course, that is a BAD thing. So, I have 
changed the labelling and presentation in the UI to make it very evident 
that the alias'd name is an alias, and in fact we display the true name 
as well.

Now, if you are telling me that creation of any new cluster with 
s-c-cluster produces a cluster named 'alpha_cluster' and not what the 
user specifies, then this is a bug and it will be fixed for the next 
update. The intended action is for the modelbuilder code to check if a 
name exists, and if not, use the alias field for the initial name of the 
cluster.

I will check this out today. Thanks.

-Jim