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Using the Command Line Interface
You can administer and use MemVerge Memory Machine using the Command Line Interface (CLI) on any installed host.
Using Snapshots in the Memory Machine CLI
Use the mvmcli snapshot command from the CLI on a Memory Machine host to capture the state of a running process, then later restore the running process to the captured state.
Using Snapshots in Memory Machine
Capturing a snapshot is almost instantaneous, requiring only that a small amount of metadata be saved to a storage device.
Copying Snapshots
You can export and import snapshots – copy them to conventional storage and back into PMEM. See oxy_ex-3/topics/t_mvmm_copying_a_snapshot_to_the_same_host.html. You can also clone an instance, creating an exact duplicate that can be run concurrently with the original process. See oxy_ex-3/topics/t_mvmm_cloning_an_instance.html. Finally, you can replicate a snapshot – copy it from PMEM on one host directly into PMEM on another host. See oxy_ex-3/topics/c_mvmm_snapshot_replication.html.
Snapshot Replication
"Snapshot replication" refers to copying a snapshot from one host to another. Only snapshots can be replicated, not running application instances.

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 Management Center
Memory Machine Management Center (M3C) is a web UI application available on the host that is running the Memory Machine Management Service. You can view system resources and performance metrics; create and restore snapshots; schedule jobs; and more in M3C.
Using the Command Line Interface
You can administer and use MemVerge Memory Machine using the Command Line Interface (CLI) on any installed host.
- MemVerge Memory Machine Administration
  MemVerge Memory Machine can be installed and run using CLI commands.
- Managing Application Memory
  To manage application memory with Memory Machine, you run the application on a data host in an environment with Transparent Memory Service (TMS) and Distributed Persistent Memory Engine (DPME).
- Using Snapshots in the Memory Machine CLI
  Use the mvmcli snapshot command from the CLI on a Memory Machine host to capture the state of a running process, then later restore the running process to the captured state.
  - Using Snapshots in Memory Machine
    Capturing a snapshot is almost instantaneous, requiring only that a small amount of metadata be saved to a storage device.
    - Preparing a System for Snapshots
      Snapshots can be captured on a host on which Memory Machine is properly configured and the data service is running.
    - Snapshot Dependencies
      Capturing or restoring a snapshot with an established IP connection requires the iptables-utils package. MemVerge recommends installing iptables-utils on any data server on which ZeroIO Snapshot is used.
    - Capturing a Snapshot with CLI
      Capture snapshots of a running application using the mvmcli snapshot create command.
    - Listing Snapshots
      List snapshots using the mvmcli snapshot list command.
    - Restoring Snapshot Images
      Restore a snapshotted application image with the mvmcli snapshot restore command.
    - Persisting a Snapshot
      You can make a snapshot persistent by forcing the snapshot data into PMEM. This is called flushing the snapshot.
    - Removing Snapshots
      Remove snapshots with the mvmcli snapshot rm command.
    - Copying Snapshots
      You can export and import snapshots – copy them to conventional storage and back into PMEM. See oxy_ex-3/topics/t_mvmm_copying_a_snapshot_to_the_same_host.html. You can also clone an instance, creating an exact duplicate that can be run concurrently with the original process. See oxy_ex-3/topics/t_mvmm_cloning_an_instance.html. Finally, you can replicate a snapshot – copy it from PMEM on one host directly into PMEM on another host. See oxy_ex-3/topics/c_mvmm_snapshot_replication.html.
      - Exporting and Importing a Snapshot
        Export a snapshot out of PMEM and onto disk storage, then import it to the same or a different host, using the mvmcli snapshot export and mvmcli snapshot export commands.
      - Cloning an Instance with CLI
        You can run duplicates of a snapshotted process on a single host using the mvmcli snapshot restore --clone command.
      - Cloning an Instance in a Network Namespace
        Clone an application instance into an existing network namespace by giving the namespace as a parameter to the mvmcli snapshot clone -c command.
      - Snapshot Replication
        "Snapshot replication" refers to copying a snapshot from one host to another. Only snapshots can be replicated, not running application instances.
        Replicating a Snapshot
        Replicate (copy) a snapshot from a source host to a target host on the same Memory Machine service using the mvmcli snapshot replicate command.
- Troubleshooting
- Preparing Intel® Optane™ DC Persistent Memory PMEM
  Prepare PMEM for use by configuring the Intel Optane DC Direct Access (DAX) devices in AppDirect mode.
- Preparing to Run an Application
  Normally you run applications by using the mm wrapper script supplied with Memory Machine. See oxy_ex-3/topics/t_mvmm_running_an_application_with_mvmm.html. If you do not use the mm to run your application, you must set up the Memory Machine environment manually before running the application.
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.
All Documentation
Links to documentation for all releases of MemVerge Memory Machine.

Snapshot Replication

"Snapshot replication" refers to copying a snapshot from one host to another. Only snapshots can be replicated, not running application instances.

Snapshot replication enables you to:

Back up an application instance to fail over to another host to protect availability.
Migrate an application instance to temporarily or permanently redistribute workloads.
Duplicate an application instance to then clone and run in parallel on another host or virtual host.

You initiate replication from the host containing the snapshot that you want to replicate, hereafter called the source host. The host that you are replicating to is the target host. The replication service works as follows:

Initiate replication with the mvmcli snapshot replicate command on the CLI of the source host. See Replicating a Snapshot. Specify the snapshot you want to replicate and the target host.
A service on the target host, mvcsnapd, accepts the request, which includes the list of files and PMEM data that comprise the snapshot.
The mvcsnapd service writes the file list and the metadata to the target host's storage.
The mvcsnapd service then copies the PMEM data from the source host to the target host PMEM.
The mvcsnapd service returns a success message to the mvmcli process on the source host.
If the replication fails, the mvcsnapd service writes error messages to its log file, mvcsnapd.log.

Memory Machine does not prevent the replicated snapshot from being restored to a runnining state on the target host, even if the instance containing the original snapshot is still running on the source machine. However, MemVerge recommends having only one running instance across the copies, otherwise undefined behavior can occur due to identity and resource conflicts. If multiple running instances are desired, each additional instance should be a separate clone of the base instance so that they each have unique identities and resources. See Cloning an Instance with CLI.