𝐕𝐌𝐰𝐚𝐫𝐞 𝐯𝐌𝐨𝐭𝐢𝐨𝐧: 𝐀𝐫𝐜𝐡𝐢𝐭𝐞𝐜𝐭𝐮𝐫𝐞, 𝐓𝐲𝐩𝐞𝐬, & 𝐑𝐞𝐚𝐥-𝐖𝐨𝐫𝐥𝐝 𝐔𝐬𝐞 𝐂𝐚𝐬𝐞𝐬-
------------------------------------------------------------------------ VMware vMotion is a VMware feature that allows a running virtual machine (VM) to move from one ESXi host to another with zero downtime. ⚙️ 𝐇𝐨𝐰 𝐃𝐨𝐞𝐬 𝐯𝐌𝐨𝐭𝐢𝐨𝐧 𝐖𝐨𝐫𝐤? vMotion works by copying VM memory and state from the source host to the destination host while the VM is still running. 𝐒𝐭𝐞𝐩-𝐛𝐲-𝐬𝐭𝐞𝐩 𝐟𝐥𝐨𝐰: ⁎ vCenter initiates migration ⁎ VM memory is copied to the destination host ⁎ Changed memory pages are tracked and re-copied ⁎ VM execution switches to the destination host ⁎ Source host releases the VM ✔️ The entire process happens in milliseconds. ✅𝐯𝐌𝐨𝐭𝐢𝐨𝐧 𝐏𝐫𝐞𝐫𝐞𝐪𝐮𝐢𝐬𝐢𝐭𝐞𝐬 Before using vMotion, these must be configured: 🔹 Infrastructure Requirements • Both hosts must be managed by VMware vCenter Server • Hosts must be in the same vCenter • Compatible CPUs • vMotion supported license 🔹 Network Requirements • vMotion VMkernel port enabled on both hosts • Same vMotion VLAN • Low-latency network 🔹 Storage Requirements • Shared datastore (for Compute vMotion) • OR different datastores (for Storage vMotion) 🔄𝐓𝐲𝐩𝐞𝐬 𝐨𝐟 𝐯𝐌𝐨𝐭𝐢𝐨𝐧 𝐢𝐧 𝐕𝐌𝐰𝐚𝐫𝐞 1️⃣ 𝐂𝐨𝐦𝐩𝐮𝐭𝐞 𝐯𝐌𝐨𝐭𝐢𝐨𝐧 Compute vMotion is used when you want to move a running virtual machine from one ESXi host to another, but you do not want to move its storage. • The VM stays powered ON during migration • Only CPU, memory, and VM execution state are moved • The VM disk remains on the same shared datastore • Users continue working without any interruption 2️⃣ 𝐒𝐭𝐨𝐫𝐚𝐠𝐞 𝐯𝐌𝐨𝐭𝐢𝐨𝐧 Storage vMotion is used when you want to move a VM’s disk files from one datastore to another, while the VM continues running on the same ESXi host. • VM remains powered ON • Only storage (VMDK files) is moved • Host does not change • No downtime for applications 3️⃣ 𝐒𝐡𝐚𝐫𝐞𝐝-𝐍𝐨𝐭𝐡𝐢𝐧𝐠 𝐯𝐌𝐨𝐭𝐢𝐨𝐧 Shared-Nothing vMotion is used when there is no shared storage between ESXi hosts. • VM compute (CPU & memory) is moved • VM storage is also copied to the destination host • VM stays powered ON • No shared datastore is required 4️⃣ 𝐂𝐫𝐨𝐬𝐬 𝐯𝐂𝐞𝐧𝐭𝐞𝐫 𝐯𝐌𝐨𝐭𝐢𝐨𝐧 Cross vCenter vMotion is used when you want to move a running VM between two different vCenter Servers. • VM remains powered ON • VM moves across vCenters • Storage and network can also change • No service interruption 🏢 𝐑𝐞𝐚𝐥-𝐓𝐢𝐦𝐞 𝐄𝐱𝐚𝐦𝐩𝐥𝐞 🔹 Scenario: Production Server Maintenance Company has 3 ESXi hosts A production VM is running on Host-1 Host-1 needs patching 👉 Without vMotion: ‑ VM must be powered off ‑ Business downtime 👉 With vMotion: ‑ Admin initiates vMotion ‑ VM moves live from Host-1 → Host-2 ‑ Users continue working ‑ Host-1 is patched safely ✔️ Zero downtime ✔️ Zero user impact
🔹 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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