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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.
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.

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.

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.

Before you begin

Ensure that the Zstandard (zstd)compression utility is installed on the host from which you are exporting. If Zstandard is unavailable, the exporter uses zip, which can be much slower.

About this task

Export snapshots from a host to:

Preserve snapshots while you reinstall Memory Machine.
Duplicate application instances on a different host.

Procedure

Take a snapshot.

# mvmcli snapshot create -p pid -l label

For example:

# mvmcli snapshot create -p 12345 -l redis-server
Snapshot redis-server_11dc085a created in 604.73 ms, application frozen for 146.44ms.

Optional: Create a directory to put the export file in. For example:
```
# mkdir /home/mvmm_user/export_dir
```

Export the snapshot as follows:

# mvmmcli snapshot export -x export_directory -l|--label snap-label

where

export_directory: is a directory in a filesystem accessible to the host.
snap-label: is a label to use as the filename of the snapshot.

For example:

# mvmcli snapshot export -x /home/mvmm_user/export_dir -l redis-server_11dc085a
Snapshot redis-server_11dc085a has been successfully exported

List the directory to which you exported the file.

# ls /home/mvmm_user/export_dir/
total 84
-rw-r--r--. 1 root root 82512 Nov 10 10:55 redis-server-f3e1d4ea

(If necessary) When you are ready to restore the snapshot, move the export file to a destination host. For example:
```
$ scp /home/mvmm_user/export_dir/redis-server-f3e1d4ea mvmm_user@target_host:/home/mvmm_user/
$
```
Another option is to export the snapshot to a shared filesystem, such as an NFS share, that is also accessible to the target host.
Import the snapshot using the mvmcli snapshot import command.
```
$ mvmcli snapshot import -x export_file
```
where

export_file

is the file path of the exported snapshot.

For example:
```
$ mvmcli snapshot import -x /home/mvmm_user/export_dir/redis-server_11dc085a
```

Restore the snapshot.

$ mvmcli snapshot restore -l export_file

where

export_file: is the file path of the exported snapshot.

For example:

$ mvmcli snapshot restore -l redis-server_11dc085a