Information Technology Reference
In-Depth Information
Examining VM Backup Methods
There are three high-level methods of backing up VMs in a VMware vSphere environment:
Running a backup agent of some sort in the guest OS
Leveraging vSphere snapshots and the vSphere Storage APIs for Data Protection (more
popularly known as VADP)
Using array-based snapshot integration
While various backup applications might have slight variations, the basic methods remain
the same. Each of these methods has its own advantages and disadvantages, and no one solution
will be the right i t for all customers.
Figure 7.33 illustrates the l ow of information when using backup agents inside the guest OS.
Figure 7.33
Running backup
agents inside
the guest OS can
provide applica-
tion- and OS-level
integration, but
not without some
drawbacks.
esxi-07.lab.local
Backup
target
App
vSwitch
Agent
VM1
vSwitch
App
Shared
datastore
VM2
Agent
As you can see from Figure 7.33, running a backup agent within the guest OS affords you
OS-level and application-level awareness and integration. The backup agent can leverage the
APIs of the guest OS to integrate with the OS and applications running in the OS (for example,
by leveraging the Volume Shadow Copy Service in Microsoft Windows). This allows the backup
agent to perform very granular backups, such as specii c tables within an SQL database, particu-
lar mailboxes in Microsoft Exchange, or a subset of i les within a Linux i lesystem.
However, running backup agents within the guest OS has its drawbacks too:
The network trafi c typically runs across the network, which can create network bottle-
necks. This is especially true if the backup trafi c runs across the same network as end
user-facing trafi c.
To avoid bottlenecks with end user-facing trafi c, organizations introduced dedicated
backup net works. This means more NICs in the ESXi hosts, separate vSwitches, separate
physical switches, additional vNICs in the VMs, and additional complexity in the guest OS
and the solution as a whole. Separate backup networks can also complicate troubleshoot-
ing and operations.
The backup agents are individually running in each guest OS instance, so as more and
more VMs (and guest OS instances) are consolidated onto physical servers, this creates
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