N-central Help

Patch Cache vs. Probe Cache

SolarWinds N-central probes use two caching systems, to store install instal files and databases. Each has a specific purpose. The information below outlines the differences to ensure you are configuring the correct one.

Patch Cache

Patch cache is a location within a customer environment where the probe downloads and stores Windows and third party patches for future distribution to the client devices. SolarWinds N-central initiates patch downloads from this cache, rather than directly to each device from the vendor or other external source. This saves bandwidth and time by providing a single source staging point for an organization. A patch cache is typically one of the probes or the only probe in your customer's environment.

The patch cache size is 40 GB. To maintain cache size, Patch Manager deletes the oldest cached files as required when the cache storage is near capacity.

When SolarWinds N-central installs a probe, it also installs the N-able Patch Repository Service that communicates on port 15000. The probe receives download requests from the agent for patch installers. The probe then downloads them from the vendor's web site to distribute to any requesting agent.

The patch cache is located in the C:\Program Files (x86)\N-able Technologies\NablePatchCache folder. Patch information is stored in the file CacheMetaData.xml, located in the patch cache folder with the installer files. You can configure the patch cache folder location and size.

Probe Cache

The probe cache is used by the probe for storing installers for various SolarWinds N-central features, including new versions of the agent, the metadata files used by the agents, and monitoring data. The probe cache does not store patch updates. For information on how the probe uses cached monitoring data, see Data persistence on Windows probes.

The Probe uses port 10004, and uses the Microsoft .NET Remoting framework.

The Probe cache is located in the C:\Program Files (x86)\N-able Technologies\Windows Software Probe\Repository folder and default the probe cache size is 500 MB.

When an agent needs installer files such as the D2D installer, or when receiving an agent upgrade action, the agent sends a request to the probe requesting a specific installer. Depending on type of installer requested, the probe either downloads the file from SIS.n-able.com or from the SolarWinds N-central server and stores it in the probe cache.

Some files appear duplicated in the repository folder because they are hard links to the same physical file.

For more information on configuring probes and the probe cache, see the topic, Probes. To configure the information SolarWinds N-central stores in the cache and for how long, see Configure probe cache for monitoring data.