Sharing vCloud Director's -Snapshot functionality These slide deck is based on vCAT3.1. It is my preparation part. Please refer version and date. It reflect if there any changes and when those changes were done.

1. vCloud Director Snapshot
By Preetam Zarey
For vZare.com
Version 1.0
Tuesday, October 08, 2013

2. Agenda
• Introduction
• Impact on the underlying infrastructure
• Snapshot Design Considerations
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3. Introduction
• Snapshot is fully supported in vCD 5.1
• Files snapshot is consists of is
▫ <vm>-<number>.vmdk and <vm>-<number>-
delta.vmdk (a.k.a. child disks, redo logs or delta disks)
▫ The <number> value might not be consistent across
all child disks from the same snapshot. The file names
are chosen based on filename availability.
▫ <vm>.vmsd
 Is a database of VM’s snapshot information.
 Primary source of information for the snapshot manager
 File contains line entries that define relationships
between snapshots as well as the child disks for each
snapshot
▫ <vm>.vmsn
 Is a file which records the memory state
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4. Use Cases
• Production Backups
▫ Recommended only for short duration e.g. during
OS patching to provide some roll back possibility
• Development/test environments
▫ Excellent solution for version control
▫ Ability to rollback saves significant time for
developers but Only for developer environment
• Third-party backup integration
▫ Backup solution using VADP needs to take
snapshot.
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5. Design Considerations
• Security
▫ To enable snapshot functionality user must have
vApp_Clone privilege
• Storage
▫ vmdk file + memorysize = total consumed disk
space
▫ In vCloud only one snapshot is allowed per VM
▫ Datastore free space monitoring is critical with
snapshot enabled environment
▫ Storage DRS automatically does that for you but it
does not stop a snapshot from writing to the
datastore when performing migrations.
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6. Design Considerations
• Performance
▫ Enable VAAI if storage supports it
▫ VAAI provides Hardware Assisted Locking (HAL)
▫ HAL offloads locking mechanism to the arrays
▫ Locking happens at much granular level than
locking entire LUN
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7. Snapshot Characteristic
• Only one snapshot per VM is permitted. Do note
that if you have a existing snapshot & If you take
another, the previous snapshot will be overwritten
• NIC settings are marked as read-only after a
snapshot is taken. Editing is disabled via API
• Snapshot storage allocation is added to chargeback
• vCloud director performs storage quota check (??)
• REST API can be used to take snapshot
• VM memory can be included in the snapshot
• Fully clone is forced when you copy(same behavior as vSphere) or
move VM, resulting in consolidation of snapshots
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8. Reference
• Good Video from VMware
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