CHAPTER 26

Advanced Administration and Command-Line Reference

17 sections · 19 min read · SimpleVM 10.1

Part XIII — Advanced Administration and Reference

Almost everything in this guide is done from the web console, and that is deliberate: the console is guided, reversible, and hard to get badly wrong. This chapter exists for the cases the console does not cover — when you need more detail than a page shows, when you are recovering from a fault, when support asks for specific output, or when you are scripting a repeatable task. The tools below expose the virtualization, storage, networking, and firewall layers that SimpleVM normally configures for you. They are powerful, and several of them are destructive. Used in the order this chapter recommends — read first, change one thing, keep a way back — they are also the fastest way to understand and repair a host.

Use it as a lookup, not a tutorial. If you know the command family you need, jump to its section (Section 26.3 through Section 26.7). If you are orienting from a VMware background, start with Section 26.8, VMware-to-SimpleVM Concepts. If you are collecting information for a support case, Section 26.16, Support Information Checklist tells you exactly what to gather. The glossary in Section 26.17 defines the terms used across the whole guide.

26.1 When to Use Advanced Administration Tools

Overview

Most day-to-day SimpleVM administration belongs in the management interface. The web console gives you a guided, reversible way to create virtual machines, read host health, manage storage pools, adjust virtual networks, review updates, and open a terminal — all without the risk that comes from typing raw commands against a live host. Reach for the command line when the console genuinely cannot do what you need:

• More detail than a page shows — full VM XML, exact pool capacity, the live routing table, or a service's recent log lines.
• Troubleshooting — confirming state and narrowing a fault when a page does not explain a symptom. The diagnostic method itself lives in Chapter 25, Troubleshooting.
• Support output — gathering the specific command output a support engineer asks for (see Section 26.16, Support Information Checklist).
• Automation — scripting a repeatable task that the console performs one click at a time.

26.2 Command-Line Administration Overview

Overview

SimpleVM is built on the standard RHEL-family virtualization stack, so the command-line tools are the same ones an experienced Linux virtualization administrator already knows. The command line does not replace the guided console for normal use, but it is valuable for verification, recovery, support, and automation. The families you will use most are below, with the risk each one carries.

The safety pattern for advanced commands

Apply the same sequence every time, regardless of which family you are using. It is the single habit that prevents most command-line accidents:

• Confirm the host. Run hostnamectl and confirm you are on the host you intend to change.
• List before you change. List the current objects — VMs, pools, networks, zones, or connections — so you know the exact name you are acting on.
• Read-only first. Run list, info, show, or status commands before any command that changes state.
• Do not run destructive commands without a recovery path. Confirm the VM data, host configuration, or network path is backed up or otherwise recoverable first.
• Document production-affecting changes. Record what you changed, on which host, and when — anything that touches production VMs, storage, networking, firewall rules, or cluster behavior.

26.3 Common VM Commands

Overview

These virsh commands inspect and control virtual machines. Use the VM name exactly as it appears in the Virtual machines list or in virsh list --all. Read-only commands are safe to run at any time; the state-changing commands are marked in the notes column.

26.4 Common Storage Commands

Overview

Storage commands verify pool status, refresh pool metadata, and collect information for support. For routine storage-pool work, use the management interface — see Chapter 12, Managing Storage Pools, and Chapter 13, Managing Host Storage. Confirm pool state on the Storage pools page before running virsh pool-* commands.

26.5 Common Network Commands

Overview

Network commands divide into two groups: the virsh net- commands for the virtual networks that VMs attach to, and the nmcli and ip commands for the host network the SimpleVM host itself uses. Be especially careful with host-network changes when you are connected remotely. Confirm virtual networks on the Networks page before running virsh net-; see Chapter 14, Managing Virtual Networks, and Chapter 15, Managing Host Networking.

26.6 Common Firewall Commands

Overview

The firewall protects the host and controls which services are reachable. SimpleVM uses firewalld with zones. Use the console for routine firewall review (see Chapter 16, Firewall and Security Settings) and firewall-cmd for detailed verification, support output, and the confirmed cluster-preparation procedure. Firewalld separates runtime and permanent configuration: a --permanent change does not take effect until you run firewall-cmd --reload.

The cluster-preparation sequence below is confirmed against the live firewall zones (see Section 26.13, Firewall Services and Ports): the cluster zone allows ssh and qemu-nbd on TCP 49152–49215. Run it on each host, adding every peer as a source:

26.7 Common Migration Commands

Overview

Migration moves a virtual machine from one SimpleVM host to another. Use the documented migration and cluster workflows first — see Chapter 21, VM Migration, and Chapter 22, Configuring Host Clusters for Live VM Migration and High Availability. Command-line migration is for advanced administration, automation, and support-guided procedures. Live migration requires compatible hosts, reachable management networking, compatible CPU capabilities, and storage and network conditions that support the chosen method; shared storage and a configured cluster may be required for high-availability workflows.

Before migrating, confirm the VM's state, disks, and interfaces:

Live migration performs a permanent move and removes the VM definition from the source host:

26.8 VMware-to-SimpleVM Concepts

Overview

If you are coming from a VMware environment, the concept map below connects familiar terms to their SimpleVM equivalents. The mappings are orientation aids, not exact one-to-one replacements — the underlying technology differs — but they shorten the learning curve by anchoring SimpleVM ideas to ones you already use.

26.9 Supported Guest Operating Systems

Overview

SimpleVM runs the common server and workstation guest operating systems supported by the underlying virtualization platform. The table below is an orientation guide only. Until the SimpleVM support policy and testing confirm a guest, do not present it to users as officially supported.

26.10 Default Paths and Directories

Overview

These directories are useful during troubleshooting and support. Most should be viewed, not edited: inspect them for diagnostics and make changes through the console or supported commands. The File browser under Tools is the safest way to inspect them without a shell — see Chapter 19, Host Administration Tools.

26.11 Default Storage Locations

Overview

A SimpleVM deployment should keep operating-system storage, VM data storage, ISO storage, and backup targets clearly separated. Exact pool names and paths vary by installation, so confirm them on the host before documenting a production standard. The installation and storage chapters are the primary source for storage planning — see Chapter 5, Post-Installation Configuration, and Chapter 12, Managing Storage Pools. The commands here confirm what exists on a deployed host.

26.12 Default Network Configuration

Overview

Verify the network configuration on each host, because production deployments may use static addressing, bonded interfaces, VLANs, bridges, or separate management and VM networks. The commands below collect a safe, read-only network summary. The default NAT virtual network is rarely the right network for production VMs, which usually need bridge networking or a purpose-built virtual network — see Chapter 14, Managing Virtual Networks, and Chapter 15, Managing Host Networking.

26.13 Firewall Services and Ports

Overview

This reference lists the firewall exposure confirmed on the live SimpleVM host. The values below are confirmed against the firewall Zones detail and are written as confirmed; environment-specific services such as DNS, NTP, and monitoring depend on your deployment.

Verify any host's exposure directly with these read-only commands:

26.14 Cluster Ports and Services

Overview

Cluster and high-availability exposure should be documented from the completed clustering chapter and kept aligned with the supported SimpleVM cluster stack. Do not add, remove, or rename cluster firewall services based on generic Linux examples. The confirmed cluster firewall requirement is the cluster zone allowing ssh (22/tcp) and qemu-nbd (49152–49215/tcp), restricted to peer source addresses, as shown in Section 26.6, Common Firewall Commands, and Section 26.13, Firewall Services and Ports.

26.15 Log File Locations

Overview

Logs confirm what happened before, during, and after an issue. Start with the console Logs page where it has what you need, then use journalctl for deeper review and support collection. Include the time the issue occurred, the affected VM name, the host name, and any change made immediately before the issue began.

26.16 Support Information Checklist

Overview

Collect this information before opening a support request or escalating internally. It gives support the context to understand the host, the affected VM, the storage and network path, and the timeline — usually enough to help on the first exchange instead of the third.

26.17 Glossary

Overview

These terms are used throughout the SimpleVM User and Administrator Guide.