Changed Block Tracking; Additional Vmware Resources - EMC Avamar 6.1 User Manual

Introduction
Required VMware knowledge

Changed block tracking

Additional VMware resources

EMC Avamar 6.1 for VMware User Guide
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Guest backup and restore requires no advanced scripting or VMware knowledge.
Avamar for VMware Image backup and restore requires moderate VMware knowledge.
Integrators should have working knowledge of actual vCenter topology in use at that
customer site (that is, which ESX servers host each datastore, and which datastores store
each virtual machine's data), and the ability to log in to vCenter with administrator
privileges.
Changed block tracking is a VMware feature that tracks which specific filesystem blocks on
a virtual machine have changed between backups.
Changed block tracking identifies unused space on a virtual disk during the initial backup
of the virtual machine, and also empty space that has not changed since the previous
backup. Avamar data deduplication performs a similar function. However, using this
feature provides valuable I/O reduction earlier in the backup process. Changed block
tracking dramatically improves performance if SAN connectivity is not available.
If changed block tracking is not enabled, each virtual machine filesystem image must be
fully processed for each backup, possibly resulting in unacceptably long backup windows,
and excessive back-end storage read/write activity.
Changed block tracking can also reduce the time required to restore ("roll back") a virtual
machine to a recent backup image by automatically eliminating unnecessary writes during
the restore process.
A comprehensive discussion of VMware technology is beyond the scope of this
publication. The following VMware documentation provides additional details:
Introduction to VMware vSphere
◆
Getting Started with ESX
◆
ESX, and vCenter Server Installation Guide
◆
Basic System Administration
◆
vSphere Web Access Administrator's Guide
◆
ESX Configuration Guide
◆
Resource Management Guide
◆