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Both VPCs and Isolated Networks in Apache CloudStack provide Layer-3 network isolation for user VMs, but they differ in design and use cases. Isolated Network An Isolated Network is a single, flat network with one virtual router. All VMs share the same subnet and routing domain. Key points: One subnet per network (e.g., 10.1.1.0/24). One virtual router handles NAT, DHCP, and firewall rules. No inter-tier routing; traffic is flat. Ideal for single-tier applications or quick deployments....

Snapshots in Apache CloudStack can exist at two levels — VM snapshots and volume snapshots — each serving different purposes and stored in different locations. VM Snapshots A VM snapshot is a hypervisor-level checkpoint of an entire virtual machine. It captures the VM’s disk state and optionally its memory, allowing fast rollback to a previous state. Key points: Stored on primary storage. Created quickly without full data copy. Can include memory state for live restore....

CloudStack components communicate across multiple networks and ports. Port Summary Table Source / Target Port(s) Purpose / Description User → Management Server 8080 / 8096 CloudStack UI / API Management Server ↔ Management Server 9090 / 8250 Clustered management coordination Management Server ↔ MySQL 3306 Database connection CPVM ↔ Management Server 8250 Console proxy and control communication SSVM ↔ Management Server 8250 Secondary storage operations (template, ISO, snapshot jobs) Virtual Router ↔ Management Server 3922 SSH control and configuration SSVM ↔ Secondary Storage (NFS) 111 / 2049 NFS mount and data transfer CPVM ↔ Hypervisors 22 / 443 Console proxy, authentication, and HTTPS access SSVM ↔ HTTP File Share 80 / 443 Template and ISO downloads User Browser ↔ CPVM 443 / 80 HTTPS console access for VM consoles Management Server ↔ Xen Hosts 22 / 80 / 443 Agent management, API communication Management Server ↔ KVM Hosts 22 Agent setup via SSH Management Server ↔ vCenter (ESXi) 443 vCenter API communication Virtual Router ↔ Secondary Storage 111 / 2049 Template and snapshot copy operations Accessing System VMs (CPVM / SSVM / VR) CloudStack deploys system VMs (such as CPVM, SSVM, and Virtual Routers) with an isolated link-local IP and restricted SSH access....

1. Template / ISO Download Workflow When a user registers a new ISO or template via a URL, CloudStack offloads the download job to the Secondary Storage VM (SSVM). Step Action Component 1 User hosts ISO/template on HTTP server External (public web server) 2 User registers the URL CloudStack UI / API 3 CloudStack sends download job to SSVM Management Server 4 SSVM downloads the file via HTTP/HTTPS Secondary Storage VM (SSVM) 5 SSVM writes the file to secondary storage (NFS) /export/secondary on Management Server 6 CloudStack marks the template/ISO as “Ready” CloudStack Database Textual Flow Diagram +----------------------------+ | CloudStack Management | +-------------+--------------+ | Registers Template/ISO URL | v +-----------------------+ | Secondary Storage VM | (SSVM) +-----------+-----------+ | Downloads via HTTP/HTTPS | v +------------------------+ | Secondary Storage (NFS)| | /export/secondary | +------------------------+ | v Marks Template as READY 2....

CloudStack supports three main hypervisors, KVM, XenServer, and VMware (vSphere/ESXi). Each integrates differently with the CloudStack management plane. Overview Feature KVM XenServer VMware (vSphere) CloudStack connects to Each host directly Pool Master vCenter API System VM control Link Local network Link Local network Management network Networking Linux bridge / OVS Network labels vSwitch / dvSwitch Storage NFS / SharedMountPoint NFS / iSCSI / FC vCenter-managed datastores Max hosts/cluster Unlimited 64 (v7....