Documentation: fixup the admin_guide

- Provide more concrete examples and explanation
- Cleanup the formatting to one sentence per line, this makes reviewing
  easier
- Point to existing docs on wal and snap instead of trying to duplicate
  it here again.
Any suggestions on something better? "Using an out-of-date data directory
can lead to inconsistency as the member had agreed to store information via
raft then re-joins saying it needs that information again." ?

On Fri, Oct 31, 2014 at 12:15 PM, Brian Waldon <notifications@github.com>
wrote:

> In Documentation/0.5/admin_guide.md:
>
> >
> > -An etcd member restarted with previously used command line arguments but a new data directory is considered a different member. And it can potentially corrupt the cluster. If you are spinning up multiple clusters for testing it is recommended that you specify a unique initial-cluster-token for the different clusters. This can protect you from cluster corruption in case of the misconfiguration metioned above.
> > +When first started, etcd stores its configuration into a data directory specified by the data-dir configuration parameter.
> > +The stored configuration includes the local member ID, cluster ID, and initial cluster configuration.
> > +It also contains the write ahead log and snapshot files that etcd needs to operate and recover after a restart.
> > +
> > +If a member’s data directory is ever lost or corrupted then the user should remove the etcd member from the cluster via the [members API][members-api].
> > +An etcd member can be re-added, after removal via the API and when started empty data-dir, by using the [members API][members-api].
> > +
> > +A user should avoid restarting an etcd member with a data directory from an out of date backup.
> > +Using an out-of-date data directory could lead to confusion since the member had agreed it had stored some information and then re-joins saying it needs that information again.
>
> This sentence is a little clunky
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/coreos/etcd/pull/1556/files#r19687711>.
>