Update README.md

Author: amiller

dstack-database/README.md

@@ -1,5 +1,47 @@
 # Distributed Database using Dstack
 
-Based on Patroni configuration of postgres, with Zookeeper for leader management.
+What happens if you put an ordinary replicated database in a TEE environment?
+You'd expect to get a free upgrade from "omission fault tolerant" to "Byzantine fault tolerant."
+Possibly we'd also benefit from blockchain observability of reconfiguration.
 
-Needs 4 nodes to tolerate 1 failure.
+To start this exploration, here's a minimal fault-tolerant database service using Zookeeper+Postgres.
+
+It's a docker-compose simulation environment for 3 nodes.
+You can crash/pause any 1 of them, and the other 2 will make progress.
+
+- `./Dockerfile` starts from postgres base image
+- `./docker-compose.yml` defines three services
+- `./patroni.yml` configures the postgres
+- `./start.sh` runs zookeeper, fixes directory permissions, runs patroni
+- `./zoo.cfg` zookeeper consensus
+
+### Try it out
+No configuration necessary, just run with docker compose
+```bash
+docker compose build
+docker compose up
+```
+### Experiment with crashing/pausing
+
+#### Crashing
+This configuration can tolerate one node crashing.
+```bash
+docker compose stop dstack-database-node1-1
+```
+You can also rejoin a node to the network:
+```bash
+docker compose start dstack-database-node1-1
+```
+
+#### Pausing
+You can also pause a node, causing its connections to drop. Pausing the leader takes a while to rearrange. 
+```bash
+docker compose pause dstack-database-node1-1
+... {wait} ...
+docker compose pause dstack-database-node1-1
+```
+
+#### Example logs
+https://gist.github.com/amiller/c5d2c516b14760bcd4320650cb73f7e1
+
+TODO: simulate partition