Architecture and Data Flow

Architecture and data flow are described in the following topics, with accompanying system illustrations.

Agentless VMware Backup Node Types

In addition to the Catalogic DPX Master Server, the following types of nodes are involved in Agentless VMware Backup.

• Proxy servers

• VMware vCenters

• VMware ESXi servers managed by VMware vCenter

• VMs

• Catalogic vStor, the Catalogic DPX Open Storage Server, or the NetApp storage systems (STORAGE_CTL nodes)

Agentless VMware Backup does not require the Catalogic DPX installed on vCenter, hosts, and VMs. The following tables summarizes requirements for installation or configuration on the different types of nodes:

Node	Requires Catalogic DPX Installation	Requires Adding to the Enterprise
Virtualization proxy servers	Yes, with Virtualization Proxy Server installation setup type selected.	Yes
VMware vCenter nodes	No	Yes
ESXi servers	No	No
VMs	No	No
Catalogic vStor Server or NetApp storage system nodes	No	Yes

Backup Architecture: SAN, LAN (NBD), and HotAdd

Backup over a SAN or VMware HotAdd is recommended for superior performance. SAN has significant advantages over LAN (NBD):

• Impact on ESX server processing is reduced. On a LAN, the ESX server needs to read VMDKs and transfer them to the proxy server. On a SAN, the proxy servers read directly from storage, bypassing ESX servers.

• Network contention is reduced.

• Network transmission time is reduced.

• Fewer connections are required on the vSphere server.

For many small- to medium-sized companies, LANs are cost-effective. In such environments, Agentless VMware Backup can be easily deployed for LAN backup, though performance is constrained by the LAN.

For HotAdd transport mode, vStorage APIs use the SCSI hot-add functionality of the ESXi host to mount a virtual machine’s associated virtual disks to backup storage, such as the Catalogic vStor server, for backup jobs. Using HotAdd requires that SCSI disks be used.

Backup Architecture: Agent-Based and Proxy-Based Backup in a Single Protection System

Proxy-based agentless backup is highly efficient for protecting many VMs, but agent-based backup with the Catalogic DPX Block Data Protection is required for protecting application servers or iSCSI-based volumes.

Restore Architecture and Data Flow

Restores are accomplished through the management console. Internally, Catalogic DPX uses LUN mapping and Storage vMotion to provide either an Instant or Full restore.

• For Instant restore of a VM or VMDK, Catalogic DPX creates a LUN on storage systems from the backup snapshot you select as the restore source. Catalogic DPX then maps the LUN to the ESX server that hosts the VM restore destination, creates a temporary datastore containing an RDM VMDK, then attaches the RDM VMDK to the VM restore target. That completes an Instant restore, and the VMDK is available for use through iSCSI LUN mapping.

• A Full restore of a VM or VMDK includes the same steps as Instant restore and then uses Storage vMotion to migrate data from one or more RDM VMDKs on the temporary datastore to flat VMDKs on a production datastore.