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Using the Command Line Tools
You can administer and use MemVerge Memory Machine using a Command Line Interface (CLI).
Using the Memory Machine Command Line Tool
You can administer and use Memory Machine using the mvmcli command line tool on any data host.
Using the Memory Machine CLI Snapshot Command
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.
Capturing a Snapshot with CLI
Capture snapshots of a running application using the mvmcli snapshot create command.

Overview and Installation
Understanding how persistent memory works is helpful when getting started with MemVerge Memory Machine. 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 Tools
You can administer and use MemVerge Memory Machine using a Command Line Interface (CLI).
- Using the Memory Machine Command Line Tool
  You can administer and use Memory Machine using the mvmcli command line tool on any data host.
  - Memory Machine CLI Command Summary
    Use the Memory Machine command line tool, mvmcli, to display PMem usage, set DRAM tier levels, manage snapshots, and manage data clusters.
  - Using the Memory Machine CLI Snapshot Command
    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.
    - Managing Memory Machine Snapshots
      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.
    - Capturing a Snapshot with CLI
      Capture snapshots of a running application using the mvmcli snapshot create command.
    - Saving Files and Directories with Snapshots
      Save files and directories with a snapshot using the savefile and savedir options with 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.
    - Restoring a TTY Session
      Restore a TTY-connected application instance on the command line, optionally using tmux to redirect the TTY session.
    - Redirecting Files on Clone or Restore
      When restoring a snapshot, redirect file access to a new file or a copy of a file with the -e|--redirect or -E|--redirect-copy option, respectively.
    - 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.
    - Snapshot Replication
      Snapshot replication refers to copying a snapshot from one host to another. Only snapshots can be replicated, not running application instances.
- Using the M3C Command Line Tool
Memory Machine Administration
MemVerge Memory Machine can be installed and run using CLI commands. Many administrative tasks can be performed using the Memory Machine Management Center web interface.
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.

Capturing a Snapshot with CLI

Capture snapshots of a running application using the mvmcli snapshot create command.

About this task

For more information about the CLI utility, see Memory Machine CLI Command Summary.

Warning: Changing an application dependency can render a snapshot unrestorable. See Upgrading Application Dependencies.

Procedure

Determine the PID of the application instance you want to capture:

$ mvmcli snapshot list
PID    User      Date Started              Command
-------------------------------------------------------------------
10918  mvmm      Mon Sep 21 14:01:59 2020  redis-server --port 6380 
Snapshots:       Date Created              Status      Label
                 Mon Sep 21 14:11:11 2020  Incomplete  test1_97e38023
                 Mon Sep 21 14:30:39 2020  Incomplete  test3_73143fac
$

Optional: Save open files along with the processes that have opened them. See Saving Files and Directories with Snapshots.

Capture the snapshot:

$ mvmcli snapshot create  -p pid_of_app  -l snapshot_name

where:

pid_of_app: is the PID of the application to be snapshotted.
snapshot_name: is a name you assign the snapshot image. A timestamp is appended to the name to create a unique snapshot label for the snapshot. (The timestamp format is YYYYMMDDHHMMSS.) You need this label to restore the snapshot image.

For example:

$ mvmcli snapshot create  -p 10918 -l test4 -F /usr/mvmm-user/config*
Snapshot test4 created in 177.29 ms, application frozen for 166.53ms.
$ mvmcli snapshot list
PID    User      Date Started              Command
-------------------------------------------------------------------
10918  mvmm      Mon Sep 21 14:01:59 2020  redis-server --port 6380 
Snapshots:       Date Created              Status      Label
                 Mon Sep 21 14:11:11 2020  Incomplete  test1_97e38023
                 Mon Sep 21 14:30:39 2020  Incomplete  test3_73143fac
                 Mon Sep 21 14:30:57 2020  Incomplete  test4_740a02c2
$