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Working with Applications
MemVerge provides additional instructions for some popular applications supported by Memory Machine, either to assist with complex setup or to support additional functionality.
Working with Hazelcast Clusters
You can take a snapshot of a distributed Hazelcast cluster running on Memory Machine managed hosts and later restore the cluster to its original state.
Preparing Memory Machine to Work with Hazelcast
To prepare for taking snapshots of the Hazelcast cluster: install Memory Machine, enable namespace restore, and provide the Hazelcast credentials to all hosts in the cluster.

Overview and Installation
Getting started with MemVerge Memory Machine requries that you understand some background information about how persistent memory works. You can then install Memory Machine on a server and begin monitoring memory usage and capturing application snapshots.
Using the Memory Machine Dashboard
You can view system resources and performance metrics, and create and restore snapshots in MemVerge Memory Machine using the Memory Machine Dashboard, a web UI application running on one of the installed hosts.
Using the Command Line Interface
You can administer and use MemVerge Memory Machine using the Command Line Interface (CLI) on any installed host.
Working with Applications
MemVerge provides additional instructions for some popular applications supported by Memory Machine, either to assist with complex setup or to support additional functionality.
- Working with Hazelcast Clusters
  You can take a snapshot of a distributed Hazelcast cluster running on Memory Machine managed hosts and later restore the cluster to its original state.
  - Preparing Memory Machine to Work with Hazelcast
    To prepare for taking snapshots of the Hazelcast cluster: install Memory Machine, enable namespace restore, and provide the Hazelcast credentials to all hosts in the cluster.
  - Preparing Hazelcast to Work with Memory Machine
    To prepare Hazelcast to work with Memory Machine Cluster Snapshot you must configure Hazelcast on each host; create a user that belongs to the Memory Machine mvmm group; run Hazelcast on each host in Active state as a background process; and register the Hazelcast cluster with Memory Machine.
  - Capturing a Cluster Snapshot
    After configuring Memory Machine and Hazelcast, use the mvmcli cluster snapshot command to capture a snapshot of the cluster state.
  - Restoring a Cluster Snapshot
    Use the mvmcli cluster snaprestore command to capture a snapshot of the cluster state.
  - Deleting Cluster Snapshots
    Delete a cluster snapshot using the mvmcli cluster snapdelete command on the Primary Coordinator host.
  - The Cluster Snapshot Command
  - Troubleshooting Hazelcast Cluster Snapshot
- Working with KVM in Memory Machine
  Running KVMs in Memory Machine requires extra setup and configuration.
- Working with Redis in Memory Machine

Preparing Memory Machine to Work with Hazelcast

To prepare for taking snapshots of the Hazelcast cluster: install Memory Machine, enable namespace restore, and provide the Hazelcast credentials to all hosts in the cluster.

About this task

Repeat the following steps on every host in a Hazelcast cluster to prepare to capture a snapshot of the cluster.

Procedure

Install Memory Machine on the host. See Installing MemVerge Memory Machine.
Start the mvcsnapd service:
```
# systemctl start mvcsnapd
#
```
Configure the mvcsnapd service to start on system boot:
```
# systemctl enable mvcsnapd
```
Enable the namespace restore feature in managed applications by adding a line to the Memory Machine application configuration file:
```
# echo 'DisableCloneInstance: true' >> /etc/memverge/mvmalloc.yml
#
```
Important: Enabling the namespace restore feature disables the Memory Machine clone feature on the host. See Cloning an Instance with CLI and Cloning an Instance with Memory Machine Dashboard.
Stop any application instances running in Memory Machine. See Stopping an Instance.
Restart the Memory Machine DPME:
```
# systemctl restart mvmallocd
#
```
Memory Machine uses the mvm_cluster_snapshot_hazelcast.sh script to communicate with the Hazelcast cluster. Set the cluster credentials in this file to allow Memory Machine to change the cluster state while taking a snapshot.
In the sbin subdirectory of the Memory Machine installation directory (the default is /opt/memverge/sbin), edit the mvm_cluster_snapshot_hazelcast.sh file to change the CLUSTER_NAME and CLUSTER_PASSWORD parameters to those for your cluster.
```
# User need to provide these credentials. They can modify this script
# to retrieve the credentials in their preferred way.
CLUSTER_NAME="your_cluster"
CLUSTER_PASSWORD="your_cluster_password"
```

What to do next

Configure the Hazelcast cluster to work with Memory Machine. See Preparing Hazelcast to Work with Memory Machine.