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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.

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.
- 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.

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.

ZeroIO Snapshot retains the actual application data in PMEM, with no time-consuming copying to storage devices. However, depending on how much data is in DRAM, the snapshot is not persistent – able to survive a server crash – until the data in DRAM is flushed to PMEM. This can require a few minutes for large applications. See Snapshot Statuses.

A snapshot of a running application process tree can be captured at any time except when:

The process tree is already in process of being snapshotted, restored, or deleted.
The process tree is attached for strace or other debug utilities.
The snapshot process is run by a nonprivileged user and the process tree was started by a different user.
The process has an open tty connection. In this case you cannot capture a snapshot using the Memory Machine Management Center, but you can still take snapshots using the mvmcli command-line utility. See Capturing a Snapshot with CLI.
Other less common conditions can prevent a snapshot as well; see a full discussion of Linux snapshots at the Checkpoint/Restore In Userspace (CRIU) website.

When a snapshotted application is restored, it begins running again in exactly the same state as when it was captured, including having the same process ID (PID). Therefore, to restore a snapshot of an application, you must stop the original application or any other processes using the process tree's PIDs. Any work done by the application between the capture and restore is lost.

To duplicate a running process, use clones. Cloning uses namespaces to circumvent PID conflicts. See Cloning an Instance with CLI and Cloning a Snapshot with Memory Machine Management Center.

To duplicate a running process on another host, for example to create redundancy in case of host failure, you can replicate a snapshot using the mvmcli snapshot replicate command. Snapshot replication duplicates the snapshot in another host's PMEM, where it can be restored as if it were on the original machine.See Snapshot Replication.