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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. 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.
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.

Overview and Installation
Getting started with MemVerge Memory Machine requires 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.
- Using the M3C Command Line Interface
- 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 MemVerge Memory Allocation Service (MVMAS).
- 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 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 snapshot of an 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. 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™ Persistent Memory PMem
  Prepare PMem for use by configuring the Intel Optane Persistent Memory 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 all technical documentation for MemVerge Memory Machine including previous releases.

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.

Before you begin

Before replicating a snapshot, make sure that the mvcsnapd and mvsvcdservices are running on the target host.

Note: The required service is mvcsnapd, not mvsnapd; note the letter "c" in the first process name. They are two separate processes and both are part of Memory Machine. See Running Memory Machine Services.

About this task

The snapshot is replicated into PMem on the target machine. The replica snapshot has the same PID as it did on the source host.

For snapshots with a parent snapshot on the source host:

If the parent snapshot already exists on the target host, the snapshot is transferred as a difference from the parent image.
If the parent does not exist on the target host, the snapshot is transferred as a complete base image.

If a snapshot with the same label already exists on the target host, the command fails.

Important: Memory Machine does not support capturing and restoring snapshots on hosts with different OS versions. This includes replicating or exporting a snapshot to a different host as well as upgrading the OS on a host between capturing and restoring a snapshot.

Procedure

To replicate a snapshot, run the following command on the source host:

$ mvmcli snapshot replicate --label snapshot_label --remote remote_mvcsnapd_ip_and_port

Where

snapshot_label

is the label of the snapshot that is to be replicated.

remote_mvcsnapd_ip_and_port

is the IP address or DNS resolvable name of the target host and port that the mvcsnapd service is configured with, for example:

10.0.0.25:5679

If you have not changed the default in the mvcsnapd.yml file, the default port is 5679.

Results

The snapshot is replicated (copied from PMem to PMem) from the source to the target host. Logs are written to the server in mvcsnapd_log (by default in the /var/log/memverge/ directory).