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Rubrik -  - Reducing the Impact of Application Stun


Reducing the Impact of Application Stun

Application stunning during the snapshot process is a topic that often bubbles up in customer conversations on data protection for VMware environments. To level set, application stun goes hand-in-hand with any snapshot operation. VMware stuns (quiesces) the virtual machine (VM) when the snapshot is created and deleted. Cormac Hogan has a great post on this here. Producing a snapshot of a VM disk file requires the VM to be stunned, a snapshot of the VM disk file to be ingested, and deltas to be consolidated into the base disk. If you’re snapping a highly transactional application, like a database, nasty side effects appear in the form of lengthy backup windows and application time-outs when the “stun-ingest-consolidate” workflow is not efficiently managed. When a snapshot of the base VMDK is created, VMware will create a delta VMDK. Write operations are redirected to the delta VMDK, which expands over time for an active VM. Once the backup completes, the delta VMDK needs to be consolidated with the base VMDK. Longer backup windows lead to bigger delta files, resulting in a longer consolidation process. If the rate of I/O operations exceeds the rate of consolidation, you’ll end up with application time-outs.Rubrik was designed…