Changes in 3022fd4: Add clarification for mongo setup.

				wiki/info/landscape/amazon-ec2.md
			
          @@ -127,8 +127,8 @@ There are currently three MongoDB replica sets:

              <img src="/wiki/info/landscape/images/MongoDBReplicaSets.png"/>

           - ``live``: Used by default for any new event or club server. The replica set consists of three nodes, two of which running on instances with fast but ephemeral NVMe storage for high write throughput, thus eligible as primary nodes; and a hidden replica with a slower EBS gp2 SSD volume that has a backup plan. The two NVMe-backed nodes have DNS names pointing to their internal IP addresses: ``mongo0.internal.sapsailing.com`` and ``mongo1.internal.sapsailing.com``. Their MongoDB processes run on the default port 27017 each. They run in different availability zones. The hidden replica runs on ``dbserver.internal.sapsailing.com:10203``.

          -- ``archive``: Used by the ARCHIVE servers (production and failover). It host a DB called ``winddb`` (for historical reasons). Its primary and by default only node is found on ``dbserver.internal.sapsailing.com:10201``. If an ARCHIVE server is launched it is a good idea to scale this ``archive`` replica set by adding one or two secondary nodes that are reasonably sized, such as ``i3.2xlarge``. Note that the ARCHIVE server configuration prefers reading from secondary MongoDB instances, thus will prefer any newly launched node over the primary.

          -- ``slow``: Used as target for archiving / backing up content from the ``live`` replica set once it is no longer needed for regular operations. The default node for this replica set can be found at ``dbserver.internal.sapsailing.com:10202`` and has a large (currently 4TB) yet slow and inexpensive sc1 disk attached. One great benefit of this replica set is that in case you want to resurrect an application replica set after it has been archived, you can do so with little effort, simply by launching an instance with a DB configuration pointing at the ``slow`` replica set.

          +- ``archive``: Used by the ARCHIVE servers (production and failover). It hosts a DB called ``winddb`` (for historical reasons). This differs to the `live`, which has a DB per event. Its primary and by default only node is found on ``dbserver.internal.sapsailing.com:10201``. If an ARCHIVE server is launched it is a good idea to scale this ``archive`` replica set by adding one or two secondary nodes that are reasonably sized, such as ``i3.2xlarge``. Note that the ARCHIVE server configuration prefers reading from secondary MongoDB instances, thus will prefer any newly launched node over the primary.

          +- ``slow``: Used as target for archiving / backing up content from the ``live`` replica set once it is no longer needed for regular operations. The DB for the event is copied into the winddb of the archive and also to the `slow` replica set, which acts as a sort of backup. However, the events remain as separate DBs on the `slow` replica set. The default node for this replica set can be found at ``dbserver.internal.sapsailing.com:10202`` and has a large (currently 4TB) yet slow and inexpensive sc1 disk attached. One great benefit of this replica set is that in case you want to resurrect an application replica set after it has been archived, you can do so with little effort, simply by launching an instance with a DB configuration pointing at the ``slow`` replica set.

           Furthermore, every application server instance hosts a local MongoDB process, configured as a primary of a replica set called ``replica``. It is intended to be used by application replica processes running on the instance, scaling with the number of replicas required, starting clean and empty and getting deleted as the instance is terminated. Yet, being configured as a MongoDB replica set there are powerful options available for attaching more MongoDB instances as needed, or upgrading to a new MongoDB release while remaining fully available, should this ever become an issue for longer-running replicas.

...	...	@@ -127,8 +127,8 @@ There are currently three MongoDB replica sets:
127	127	<img src="/wiki/info/landscape/images/MongoDBReplicaSets.png"/>
128	128
129	129	- ``live``: Used by default for any new event or club server. The replica set consists of three nodes, two of which running on instances with fast but ephemeral NVMe storage for high write throughput, thus eligible as primary nodes; and a hidden replica with a slower EBS gp2 SSD volume that has a backup plan. The two NVMe-backed nodes have DNS names pointing to their internal IP addresses: ``mongo0.internal.sapsailing.com`` and ``mongo1.internal.sapsailing.com``. Their MongoDB processes run on the default port 27017 each. They run in different availability zones. The hidden replica runs on ``dbserver.internal.sapsailing.com:10203``.
130		-- ``archive``: Used by the ARCHIVE servers (production and failover). It host a DB called ``winddb`` (for historical reasons). Its primary and by default only node is found on ``dbserver.internal.sapsailing.com:10201``. If an ARCHIVE server is launched it is a good idea to scale this ``archive`` replica set by adding one or two secondary nodes that are reasonably sized, such as ``i3.2xlarge``. Note that the ARCHIVE server configuration prefers reading from secondary MongoDB instances, thus will prefer any newly launched node over the primary.
131		-- ``slow``: Used as target for archiving / backing up content from the ``live`` replica set once it is no longer needed for regular operations. The default node for this replica set can be found at ``dbserver.internal.sapsailing.com:10202`` and has a large (currently 4TB) yet slow and inexpensive sc1 disk attached. One great benefit of this replica set is that in case you want to resurrect an application replica set after it has been archived, you can do so with little effort, simply by launching an instance with a DB configuration pointing at the ``slow`` replica set.
	130	+- ``archive``: Used by the ARCHIVE servers (production and failover). It hosts a DB called ``winddb`` (for historical reasons). This differs to the `live`, which has a DB per event. Its primary and by default only node is found on ``dbserver.internal.sapsailing.com:10201``. If an ARCHIVE server is launched it is a good idea to scale this ``archive`` replica set by adding one or two secondary nodes that are reasonably sized, such as ``i3.2xlarge``. Note that the ARCHIVE server configuration prefers reading from secondary MongoDB instances, thus will prefer any newly launched node over the primary.
	131	+- ``slow``: Used as target for archiving / backing up content from the ``live`` replica set once it is no longer needed for regular operations. The DB for the event is copied into the winddb of the archive and also to the `slow` replica set, which acts as a sort of backup. However, the events remain as separate DBs on the `slow` replica set. The default node for this replica set can be found at ``dbserver.internal.sapsailing.com:10202`` and has a large (currently 4TB) yet slow and inexpensive sc1 disk attached. One great benefit of this replica set is that in case you want to resurrect an application replica set after it has been archived, you can do so with little effort, simply by launching an instance with a DB configuration pointing at the ``slow`` replica set.
132	132
133	133	Furthermore, every application server instance hosts a local MongoDB process, configured as a primary of a replica set called ``replica``. It is intended to be used by application replica processes running on the instance, scaling with the number of replicas required, starting clean and empty and getting deleted as the instance is terminated. Yet, being configured as a MongoDB replica set there are powerful options available for attaching more MongoDB instances as needed, or upgrading to a new MongoDB release while remaining fully available, should this ever become an issue for longer-running replicas.
134	134