🔹 VSS & VDS (in Virtualization / IT Infrastructure)
These terms are commonly used in virtualization environments like VMware. ⸻ 🖥️ VSS – Virtual Standard Switch A Virtual Standard Switch (VSS) is a virtual network switch that works on a single ESXi host. • Created and managed individually on each host • Configuration must be done separately on every host • Suitable for small environments • Simple and easy to manage 👉 Example: In a small company using VMware ESXi, each host can have its own VSS. ⸻ 🌐 VDS – Virtual Distributed Switch A Virtual Distributed Switch (VDS) works across multiple ESXi hosts. • Managed centrally through VMware vCenter Server • Same network configuration applied to all hosts • Better for large data centers Advanced features like: • Network I/O control • Port mirroring • Centralized management
🔹 Step-by-Step Explanation of Ballooning, Compression & Swapping in VMware ⸻ 1️⃣ Memory Ballooning (vmmemctl) Ballooning is the first memory reclamation technique used when ESXi detects memory pressure. ➤ Step-by-Step: How Ballooning Works 1. VMware Tools installs the balloon driver (vmmemctl) inside the guest OS. 2. ESXi detects low free memory on the host. 3. ESXi inflates the balloon in selected VMs. 4. Balloon driver occupies guest memory, making the OS think RAM is full. 5. Guest OS frees idle / unused pages (because it believes memory is needed). 6. ESXi reclaims those freed pages and makes them available to other VMs. Why Ballooning Happens? • Host free memory is very low. • ESXi wants the VM to release unused pages before resorting to swapping. Example • Host memory: 64 GB • VMs used: 62 GB • Free: 2 GB → ESXi triggers ballooning • VM1 (8 GB RAM): Balloon inflates to 2 GB → OS frees 2 GB → ESXi re...
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