What Is a Shadow VRA?

KB Number:


When working with Zerto Virtual Replication, an administrator may notice a new VM, labeled "Z-VRAH" followed by a string of numbers, listed in their datacenter.  What is this VM and what does it do?


VMware imposes a limitation of 15 SCSI targets per SCSI controller and 4 SCSI controllers per virtual machine.  This amounts to a limitation of 60 SCSI targets per virtual machine.  VRAs, which serve as hosts for replica volumes, may require access to SCSI targets beyond this limit.  Zerto Virtual Replication uses a Shadow VRA to get around this limitation.
What is a Shadow VRA?
  • A Shadow VRA is a VM linked to a VRA, which provides additional available SCSI targets.  
  • A Shadow VRA does not have an OS and therefore does not have an IP address or use VMware tools.
  • A Shadow VRA is created proactively at the target site and prior to the target VRA reaching the SCSI target limit.
  • Similar to a VRA, a Shadow VRA must be left to Zerto Virtual Replication to manage, and must not be modified for any reason.

Affected Versions:
All versions

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