In today's world, virtual servers play an important role in IT infrastructure. Virtual machines enable dynamic allocation of resources, increased availability, and, last but not least, cost savings. Larger companies, in particular, rely heavily on reliable virtual machines, which is why virtual machine monitoring is essential. VM Monitoring allows you to monitor the virtual machines, the hypervisors, and the physical servers on which they are running. This ensures that you are always aware of availability and performance, and can react quickly in the event of any errors or failures. We have compared the best virtual machine monitoring tools and offered our recommendations. Paessler PRTG Network Monitor Source: Paessler A great advantage of Paessler PRTG is the simple and straightforward interface, as well as the intuitive operation. A great addition to the PRTG software is the free tools for mobile devices. What we also really like about PRTG is the all-in-one approach. All features are included in every license, so you don't need any paid add-ons if you want to monitor traffic or devices like routers, switches, or printers in addition to virtual machine monitoring. The licensing costs of PRTG Network Monitor depend on the number of sensors you need (number of measuring points) and start at a very fair price of $1799 for 500 sensors. For very large and distributed networks Paessler offers its own solution, PRTG Enterprise Monitor. What you should consider with Paessler PRTG Network Monitor: A Windows server is required for installation, a Unix version is not (yet) available. For Unix-only networks or if you want maximum flexibility, we recommend the SaaS version PRTG Hosted Monitor. More about Virtual Machine Monitoring with PRTG can be found here. LogicMonitor Source: LogicMonitor LogicMonitor is a network monitoring tool that keeps an eye on your entire network environment. With 2000 out-of-the-box integrations, many aspects of your network can be added to the monitoring with just a few clicks. For virtual machines, vendors such as VMware, HyperV, and Citrix are supported. In addition to the comprehensive functions, LogicMonitor offers the advantage of a user-friendly interface and simple setup and configuration. LogicMonitor is available exclusively as a cloud-based SaaS variant and can therefore be used on any platform. For the full range of functions and monitoring of more than 200 devices, an enterprise license is required. The costs are billed according to monitored devices and amount to around $20 per device and month for Enterprise. The flexibility of this license has its advantages, but in the long run, it can be very expensive depending on the size of your network. In addition, LogicMonitor relies on a continually available and high-performing Internet connection. More about Virtual Machine Monitoring with LogicMonitor can be found here. ManageEngine Applications Manager Source: ManageEngine Applications Manager is an application performance monitoring tool from ManageEngine that enables you to monitor the performance and availability of your applications and services on your network. The tool allows you to monitor virtualizations from VMware, HyperV, Citrix, or Nutanix, keeping an eye on both the physical servers and the virtual machines and applications running on them. When certain thresholds are exceeded, an alarm is automatically triggered to notify the admin of any malfunction via SMS or email. Learn more about VM Monitoring with ManageEngine Applications Manager here. With several configurable widgets, you can assemble your own dashboards and reports in ManageEngine Applications Manager. Unlike Paessler PRTG and LogicMonitor, you cannot monitor your entire network when you purchase an Applications Manager license. The basic network monitoring features are provided by the ManageEngine OpManager, for more features you need additional products like the NetflowAnalyzer or the ApplicationManager. Monitoring all aspects of your network can thus quickly become very expensive. Even the license for the Applications Manager itself is relatively expensive, starting at just under $20,000 one-time or $10,000 annually. SolarWinds Virtualization Manager Source: SolarWinds SolarWinds offers a number of different tools for network monitoring and management. For VM monitoring, the Virtualization Manager (VMAN) is the tool of choice as part of the SolarWinds Orion platform. SolarWinds VMAN gives you comprehensive visibility into the health and performance of VMware vSphere, Nutanix AHV or Microsoft Hyper-V systems. Central dashboards visualize various metrics such as utilization and performance. You also get recommendations for optimal VM size and placement. If you want to monitor not only the virtual machines themselves but also the physical servers, the SolarWinds Server & Application Monitor product is also required. Similar to ManageEngine, you will need a number of other tools such as Network Performance Monitor or Server & Application Monitor for comprehensive monitoring of your entire network. Depending on your needs and the size of your network, this can quickly add up to many thousands of dollars. If you only need Virtualization Manager, licensing costs to start at around $1500. The Server & Application Monitor tool starts at around $1,400. Click here to get SolarWinds Virtualization Manager. Nagios Source: Nagios If you prefer an open-source solution for monitoring your virtual machines, Nagios is the tool of choice. The Linux-based Nagios can be adapted to your needs in an extremely detailed way via plugins. However, this customization and setup to your network require a lot of time and know-how. With Nagios, you can monitor the virtualization solutions of all major manufacturers and quickly notice when systems or services fail or do not function as desired. The basic version of Nagios Core is free of charge. For configuration wizards and individual technical support, you need the paid version Nagios XI, which starts at about $2000. More about Nagios products can be found here.