Created Filer Store Replication (markdown)

Filer-Store-Replication.md

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+# Goal
+
+* Synchronize the meta data in the filer stores. 
+* Active-Active or one-directional replication.
+
+# Use Cases
+
+For filer stores using shared filer stores, such as shared Mysql/Postgres/Cassandra/Redis/etc in [[Filer-Stores]], this is not really needed, since all filers are stateless.
+
+But if each filer has its own filer store, usually with the default local leveldb, or even with a dedicated Mysql/Postgres/Cassandra/Redis/etc store, this would be very useful.
+
+# One-Directional Replication
+
+When starting a filer, set the `-peers` option, to receive updates from the peers.
+
+Assuming there is a separate filer.toml for each filer, and a filer is already running at `localhost:8888`, this command will replicate metadata in `localhost:8888` to `localhost:8889`.
+
+```
+weed filer -port=8889 -peers=localhost:8888
+```
+
+# Active-Active Replication
+
+```
+weed filer -port=8888 -peers=localhost:8888,localhost:8889
+weed filer -port=8889 -peers=localhost:8888,localhost:8889
+```