Controlling full sync
When you subscribe a VM to a CDP enabled protection plan, NetBackup initiates full sync, to get the entire data of the newly protected VM. For a newly subscribed VM, NetBackup does not have any data to apply the incremental backup features, hence full sync is initiated. During a full sync, NetBackup captures the entire data of the VM, from the underlying VMDKs to the CDP staging location, and subsequently to the NetBackup STUs.
Full sync is normally triggered when you subscribe a new VM to a CDP enabled protection plan, but in certain scenarios, you can manually trigger a full sync:
Accidental corruption or deletion: CDP maintains backed up data of the VMs at the staging location in proprietary format files. If these files for a VM are accidentally deleted or corrupted, the subsequent backup job for the VM fails citing data integrity mismatch. In this case, you can initiate a force rescan schedule backup, and subsequently a full sync of the VM takes place.
Following a manually triggered force-rescan schedule.
CDP service can trigger full sync to receive VM data whenever necessary.
During full sync, data flows from the ESXi to the CDP gateway. Depending on the data size of the VMs, the volume of this data can be substantially large that can consume a lot of resources like network, memory, processing power, and storage. This also affects the backup operations of the VMs subscribed earlier.
If you subscribe more than 5 VMs at a time, say 7, then, full sync is initiated for 5 VMs, and 2 are in wait state.
Therefore, it is recommended to limit the number of concurrent full sync operations to optimize system resources. The default number of concurrent full sync is 5. This allows 5 VMs to perform full sync concurrently. Other VMs needing full sync need to wait in a queue. This way, the system resources are managed optimally.
Recommendation for controlling full sync:
Subscribe the VMs in batches of five or less.
Once a subscribed VM completes full sync, you can see message in the UI, then you can proceed to subscribe the next batch.
nbcct.conf fileYou can configure the number of concurrent full sync operations by specifying a value for the CCT_MAX_FULL_SYNC_REQS parameter, in the nbcct.conf file. For example, CCT_MAX_FULL_SYNC_REQS=7