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



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


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