How to Determine Max Journal Size for VMs Utilizing Zerto Service Profiles
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When replicating to vCD, an administrator may want to know how Zerto Virtual Replication Service Profiles control the Max Journal Size for a VM. This article explains the logic that dictates the behavior.
Replication to cloud sites is managed with Service Profiles, configured via the Zerto Cloud Manager (ZCM).
Part of the configuration of a Service Profile is to select a percentage value to assign for the “Max Journal Size”. This setting dictates the size of the journals of VMs within VPGs configured to use a given Service Profile, as the journal size is dynamically calculated as this percentage of the sum total of the protected volumes of the VM.
The actual sizes of the resultant journal volumes are then determined by rounding up towards the first equal-or-higher value in the following list in units of GB:
10, 15, 20, 25, 30, 35, 40, 45, 50, 75, 100, 150, 200, 250, 300, 400, 500, 750, 1000
For example if a protected VM has a sum total of 100GB of protected volumes and the “Max Journal Size” value of the the Service Profile configured for use with its VPG is 6%, the Max Journal Size for this VM will be 10GB. If a 100GB volume is added to this VM, the Max Journal Size for the VM will be increased to 15GB.