DL4300 Appliance
Understanding Rapid Snap for Virtual
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Agentless Hyper-V protection has many of the same capabilities as traditional protection where the Agent is
installed on every VM, including:
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Archiving
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Recovery point integrity checks
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Mounting recovery points
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Auto discovery of new VMs (unique to agentless protection)
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Replication
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Restoring VMs
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Restoring CSVs
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Restoring on CIFS using VHDX format
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Restoring files in a guest VHDX format
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Rollup
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Virtual export to Hyper-V VMs and other hypervisors, including ESXi, VMware Workstation, and VirtualBox
However, there are limitations to consider when choosing agentless Hyper-V protection. Capabilities that are not
performed include:
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Exchange mount integrity check
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SQL attachability check
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Live Recovery
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Restoring VMs on CIFS using VHD format
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Restoring files in a guest VHD format
NOTE:
For an application-consistent snapshot, you must have the SCSI Controller installed on each VM.
Without this controller, the result is always a crash-consistent snapshot.
Parent topic
Benefits of installing VMware Tools for agentless protection
When protecting virtual machines (VMs) without the using Rapid Recovery Agent, Dell recommends installing
VMware Tools on protected VMs on vSphere or ESXi hosts to take full advantage of Microsoft Volume Shadow
Services (VSS) functionality.
Agentless protection uses the snapshot technology native to VMware to back up protected data. When VMware
Tools are installed on a VM with a Windows operating system (OS), the backups that the Rapid Recovery Core
captures can also use VSS. When VMware Tools are not installed, Rapid Recovery still collects snapshots, but
the absence of VMware Tools can adversely affect the state of data on your protected VM.
There are two possible data states:
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Crash-consistent. The VM OS starts and can read and understand the file system.
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Application consistent. The VM OS starts and can read and understand the file system. Also, files for transactional
applications are in a consistent state. For example, with SQL Server, the logs match the database files, and the database
opens quickly and easily.
If you recover a transactional application from a crash-consistent state, the database returns to the last valid state.
That most recent valid state may be from the time of the crash, or it may be from earlier than the crash. If it is
from earlier, then the database must roll forward some work to make the data files match the information in the
logs. This process takes some time when you first open the database, which causes a delay when starting up the
machine.
