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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.
MemVerge Memory Machine Administration
MemVerge Memory Machine can be installed and run using CLI commands.
Distributed Persistent Memory Engine
The Distributed Persistent Memory Engine (DPME), mvmallocd, is a service that maps programmatic memory to PMEM. See oxy_ex-3/topics/a_mvmm_dpme_intro.html.
Stopping the Distributed Persistent Memory Engine
Stop the DPME service using the systemctl utility.

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.
  - Upgrading Memory Machine
    To upgrade Memory Machine, run the Memory Machine Package File on each host.
  - Uninstalling the MemVerge Memory Machine Data Service
    Uninstall the Memory Machine data service by running the Memory Machine uninstall script, uninstall.sh.
  - Upgrading Application Dependencies
    Upgrading dependency packages for snapshotted applications may render existing snapshots of that application unrestorable.
  - Understanding the Software License
    You must have a valid license to run Memory Machine. The license file is read at startup by the Distributed Persistent Memory Engine (DPME). Without a license, DPME defaults to running applications using only DRAM.
  - Running Memory Machine Services
    Four Memory Machine services must be running to enable PMEM management and the Memory Machine Dashboard.
  - Distributed Persistent Memory Engine
    The Distributed Persistent Memory Engine (DPME), mvmallocd, is a service that maps programmatic memory to PMEM. See oxy_ex-3/topics/a_mvmm_dpme_intro.html.
    - Configuring HugePages
      Configure Linux HugePages for DPME DRAM caching by calculating how many HugePages your system needs and setting the vm.nr_hugepages kernel parameter to that value.
    - Setting Volatile Tier Memory
      To take advantage of the speed of volatile memory (DRAM), the Distributed Persistent Memory Engine (DPME) caches the most recently used memory on the local machine’s DRAM. See oxy_ex-3/topics/a_mvmm_dpme_intro.html. You can enable tiering and set a maximum tier memory size for each application.
    - Resizing Volatile Tier Memory
      Resize the DRAM tier memory during runtime to balance performance with memory resource cost using the mvmcli dram resize command.
    - Checking Distributed Persistent Memory Engine Status
      Use the systemctl status command to confirm the DPME process is running.
    - Stopping the Distributed Persistent Memory Engine
      Stop the DPME service using the systemctl utility.
  - Running an Application in Memory Machine
    To run an application with Memory Machine memory management, use the mm script supplied with Memory Machine.
  - Using the Memory Machine Command Line Tool
    Memory Machine provides a command line tool, mvmcli, to show PMEM usage, set DRAM tier levels, manage snapshots, and manage data clusters.
  - Resetting a Host
    Reset a host by removing all snapshot and log data and initializing the DAX devices. This erases the host's PMEM.
  - Reporting Tiering Statistics
    Use the mvmcli command to view information about paging activity between PMEM and the DRAM performance tier for an application.
  - Viewing Logs
    You can examine the Memory Machine log files, for example to troubleshoot errors.
- 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.
- 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.

Stopping the Distributed Persistent Memory Engine

Stop the DPME service using the systemctl utility.

About this task

Since DPME is run as a service, you use the systemctl utility to start, stop, and view the status of the DPME process.

Procedure

Capture snapshots of any application instances that you want to restart later. See Capturing a Snapshot with CLI or Capturing a Snapshot Using Memory Machine Dashboard (Advanced Edition only).
Stop all application instances currently running in DPME.
Identify running processes by PID and kill those processes. Or, stop the processes from the Memory Machine Dashboard. See Stopping an Instance.

Warning: Shutting down DPME while managed applications are still running can cause those applications to fail with memory allocation errors.

To stop the DPME service (the mvmallocd process):

# systemctl stop mvmallocd

For example:

# systemctl stop mvmallocd
● mvmallocd.service - MemVerge Memory Engine
   Loaded: loaded (/etc/systemd/system/mvmallocd.service; disabled; vendor preset: disabled)
   Active: inactive (dead)