>
> I think it's better to use IP to store RRDs. The host names can be
> resolved
> by webfrontend and cached. The cache can be refreshed by removing old
> names,
> or edit by hands. For server farms which use kerberos, dns reverse lookup
> could returns uninteresting and unfriendly formatted names; in this
> situation,
> the ip to hostname translation can be delegated to a plugin or
> something like,
> which reads a database or a flat file.
IP may be dynamic (e.g. DHCP environment) - however, I think IP should
be an option for those who want to do it this way.
>
> In our server farm, hosts are changing roles now and then, and moved
> among
> clusters. Every time we move hosts among clusters, we get "dead" hosts in
> the old cluster and they're alive in other cluster. Restarting gmetad is
> really a bad option, you know. So the current "store by cluster and
> hostname"
> is not convenient. Ok, I know it's convenient for the situation that
> some other
> host B takes over a name that host A once used; this is service oriented.
>
I face a similar problem with hosts being re-purposed (e.g. from DR to
production and then back again). Some hosts may participate in
providing multiple services - it is not a 1-1 relationship.
> I think UUID is not a good idea, especially considering the OSes are
> reinstalled but roles ramain. We don't need a forever dead host which
> actually
> comes back to life.
UUID can be copied when necessary (e.g. rebuilding a host with the same
name and same purpose, just a fresh OS install, restore the UUID from a
backup gmond.conf) or re-generated (rebuilding a host for a new
purpose). However, as commented for IP addresses, this UUID should be
an option rather than the only way.
UUID (and IP addresses) could be announced in some kind of metric or
they could be extra fields in the <host> element. Some kind of
configurable `routing' logic in gmetad could then decide how to store
the data. E.g. it might wait until a UUID metric arrives, and then
start storing the metrics under /var/lib/ganglia/${UUID}/*.rrd or maybe
/var/lib/ganglia/${CLUSTER}/${UUID}/*.rrd - the point is, the
administrator would be able to configure the path template and some
other logic.
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