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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 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 state captured in the snapshot.
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 – using the mvmcli command. 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.
Cloning an Instance with CLI
You can run duplicates of a snapshotted process using the mvmcli snapshot restore --clone command.

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.
- MemVerge Memory Machine Administration
  MemVerge Memory Machine can be installed and run using CLI commands.
- Using Snapshots in the Memory Machine CLI
  Use the mvmcli 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 state captured in the snapshot.
  - 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 with the Memory Machine CLI utility, mvmcli.
    - Listing Snapshots
      List snapshots using the mvmcli snapshot list command.
    - Restoring Snapshot Images
      Restore a snapshotted application image with the Memory Machine CLI utility, mvmcli.
    - 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 – using the mvmcli command. 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.
      - 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 commands.
      - Cloning an Instance with CLI
        You can run duplicates of a snapshotted process 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 parameter.
- Troubleshooting
- Preparing Intel Optane DC PMEM
  Prepare PMEM for use by configuring the Intel Optane DC Direct Access (DAX) devices in AppDirect 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.

Cloning an Instance with CLI

You can run duplicates of a snapshotted process using the mvmcli snapshot restore --clone command.

Before you begin

About this task

To clone a snapshot, Memory Machine creates a new PID namespace. The snapshot to be cloned is then run in the new PID namespace, with the original PID. In this way:

The OS can see the cloned process in the original namespace (though with a new PID)
The cloned process is identical to the snapshot and has the same PID (though running in a subordinate namespace)
Any number of processes can be cloned from a single snapshot and run in their own PID namespaces as described above

Procedure

To clone an instance, type the following:

# mvmcli snapshot restore  -l|--label label
        -c|--clone
        -d|--detached

where:

label: is the label of the snapshot to restore.
-c or --clone: causes the restored process to clone the instance by restoring the snapshot to its original PID in a different PID namespace.
-d or --detached: causes the restored process to detach from the command-line shell. Default is to not detach, so that the terminal shell is owned by the restored application.

Results

A new process is created, running the snapshot in a subordinate PID namespace as described above. For example:

# mvmcli snapshot restore -l redis_player_1_ae204956 -c -d
Restore finished. Process detached. Resuming tasks
#
# mvmcli snapshot list -n redis-server
PID    User      Date Started              Command
-------------------------------------------------------------------
18074    root      Tue Aug 25 15:39:13 2020  /root/redis-5.0.7/src/redis-server *:9001
Clone:           PID
                 27424
Snapshots:       None
-------------------------------------------------------------------
18074    root      Mon Aug 17 22:52:53 2020  /root/redis-5.0.7/src/redis-server *:9001
Snapshots:       Date Created              Status      Label
                 Tue Aug 18 12:39:18 2020  Persisted   redis_player_1_ae204956
-------------------------------------------------------------------
18074    root      Tue Aug 25 15:40:22 2020  /root/redis-5.0.7/src/redis-server *:9001