WIP manual backup

op_guide/stolon/README.md

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+  - [Initialize the cluster](install.md)
+  - [Create a database](create_database.md)
+  - [Manually backup all the databases](manual_backup.md)

op_guide/stolon/manual_backup.md

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+## Disclaimer
+
+Do **NOT** use the following backup methods on the Stolon Cluster:
+  1. copying the data directory
+  2. `pg_dump`
+  3. `pg_dumpall`
+
+The first one will lead to corrupted/inconsistent files.
+The second and third ones put too much pressure on the cluster.
+Basically, you will destroy it, in the following ways:
+  - Load will increase, requests will timeout
+  - RAM will increase, the daemon will be OOM (Out Of Memory) killed by Linux
+  - Potentially, the WAL log will grow a lot
+
+
+## A binary backup with `pg_basebackup`
+
+The only acceptable solution is `pg_basebackup` with **some throttling configured**.
+Later, if you want a SQL dump, you can inject this binary backup on an ephemeral database you spawned solely for this purpose on a non-production machine.
+
+First, start by fetching from Consul the identifiers of the replication account.
+Do not use the root account setup in Stolon, it will not work.
+
+First setup a SSH tunnel on your machine that bind postgresql, eg:
+
+```bash
+ssh -L 5432:psql-proxy.service.2.cluster.deuxfleurs.fr:5432 ...
+```
+
+Then export your password in `PGPASSWORD` and launch the backup:
+
+```bash
+export PGPASSWORD=xxx
+
+pg_basebackup \
+  --host=127.0.0.1 \
+  --username=replicator \
+  --pgdata=/tmp/sql \
+  --format=tar \
+  --wal-method=none \
+  --gzip \
+  --compress=6 \
+  --progress \
+  --max-rate=2M
+```
+
+*Take a cup of coffe, it will take some times...*
+
+## Importing the backup
+
+## Dump SQL