Virtual Machine and Template Management
VM building blocks
Every VM has a hardware version that must be supported by the host's ESXi version and by the vCenter managing it. Guest OS selection drives supported devices and customization behavior. VMware Tools enables quiesced snapshots, graceful shutdown, and guest customization. Disk provisioning choices are thin, thick lazy zeroed, and thick eager zeroed; thin is the usual default and grows on demand.
Templates and content libraries
A template is a non-runnable image: it cannot be powered on, only cloned or converted back. Content libraries (local, published, subscribed) store VM templates and OVF/OVA items and let you share them across vCenters. Guest customization specifications apply hostname, IP, domain and licensing at deploy time and depend on a supported guest OS plus VMware Tools (or cloud-init for Linux).
Snapshots and clones
The snapshot chain uses delta disks; a VM supports up to 32 snapshots in a chain. Snapshots are not backups, do not survive consolidation without care, and grow indefinitely if left in place. "Consolidate" re-parents orphaned deltas after a failed delete. Clones can be full or linked, and can be customized on the fly.
Traps
Frequent distractors: powering on a template, deploying a VM with a hardware version newer than the host supports, assuming memory snapshots are free, and confusing "clone to template" with "convert to template" (the latter replaces the VM). Also expect questions about which snapshot operation quiesces the guest.
Rule of thumb
If a deployment needs a fixed baseline, publish it through a content library rather than copying VMs by hand, and keep at most two or three short-lived snapshots per VM.