CloudStack uses several System VMs to provide infrastructure services.
The main ones you’ll encounter are:
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Virtual Router (VR) – Provides network services such as DHCP, DNS, NAT and routing depending on the network configuration.
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Console Proxy VM – Provides console access to user VMs.
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Secondary Storage VM (SSVM) – Handles operations involving secondary storage, such as templates, ISOs and snapshots.
These VMs are managed by CloudStack and are different from normal user-created VMs.
One important troubleshooting point: if a customer’s VM has a networking problem, don’t only inspect the customer VM. The Virtual Router may be part of the actual problem.