Persistent Regions

This example demonstrates VMware GemFire persistent regions.

The data for a region resides in memory in the JVM for the server. When a region is persistent, the data for that region is also preserved in a disk store. The disk store uses a directory in a file system to save the operations on regions. Unlike non-persistent regions, the data for a persistent region is available even after a period where no servers for that region are running.

This example assumes you have installed JDK11 and GemFire.

Steps

From the gemfire-examples/persistence directory, build the example, and run unit tests.
```
 $ ../gradlew build
```
Next start a locator, start a server, create a disk store, and create a persistent region.
```
 $ gfsh run --file=scripts/start.gfsh
```
Run the example to increment an entry the region.
```
 $ ../gradlew run
```

Observe that the first time an initial value is used.

 Initialized counter to 0
 Incremented counter to 1

Restart down the server.

 $ gfsh run --file=scripts/restart.gfsh

Run the example to increment an entry the region.
```
 $ ../gradlew run
```
Observe that the second time the previous value is used.
```
 Retrieved counter of 1
 Incremented counter to 2
```
Shut down the system.
```
 $ gfsh run --file=scripts/stop.gfsh
```