[Gluster-devel] How do we identify peers?

[Kaushal M]

Hi all,
We have a problem with how we identify peers in GlusterFS which we
need to solve.

Peers in GlusterFS are currently identified using two keys.
 - the address of the peer (hostname/ip)
 - a UUID
The address is used as an identifier in the gluster cli commands and
is the key visible to the users of glusterfs. The UUID is used
internally by glusterd to identify peers.
This approach works well when we are using glusterfs on systems with
single network interfaces and when we are using a hostname as the
address. We run into problems when we multiple network interfaces are
involved or if hostname and ips are mixed in gluster cli commands.
Bug-890502 [1] is a good example of the problems we have. This bug
involves usage of multiple interfaces as well as mixing of
hostname/ip.

We need to come up with a good solution to this which would solve this.

Some of the solutions that have been thought of are below.

1. Continue with the current implementation of using UUID internally
and addresses externally, but provide a good translation interface
which will translate a given address into UUID correctly. The
translation interface might involve some network requests which could
increase the time taken for command execution.

2. Use the UUID itself both internally and externally, and have a
command for associating a list of addresses with a UUID. The downside
is that typing out UUIDs is unwieldy and users will need users to
execute more commands.

3. Similar to 2, but use an alias for the peer externally instead of
the UUID. This will need an additional mechanism to specify the alias
for a peer. This approach will need users one additional command
compared to approach 2, but the other commands will be simpler to
type.



What are your thoughts about the problem and the proposed solutions?
If anyone has any questions regarding the problem or the solutions, or
if there is a better solution, please sound off.

Thanks,
Kaushal