The Hyper-V Replica Log (HRL) file is a log file that be created once the initial replication of a VM is completed.
Hyper-V Replica will start monitoring the changes of each selected virtual hard disk, all the changes will be logged in the HRL file.
The HRL files are kept in the same directory where the Virtual Machine VHD/VHDX reside. Each VHD file, which has been selected for the replication has an associated HRL file.
The changes are tracked at the virtual machine level for example. any changes (write operations) to the virtual machine are tracked and stored in the HRL log files.
Once the replicas/HRL files are ready, "Replication Manager" notifies "Replication Tracker (RT) to send the copies to the Replica Server.
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