Figure 8.12 ASR architectural overview for replication from Hyper-V to Azure
You may notice a large number of files, as shown in Figure 8.13. Don’t panic; this is
normal. Rather than merge HRL files as they arrive, a process runs periodically to
merge in HRL files, or it is triggered if a failover is performed.
Figure 8.13 View of Azure storage account containing Hyper-V Replica target VM
While the focus of this book is Hyper-V, Azure Site Recovery also has a guest-based
agent replication. (Hyper-V is a host agent since the replication is at the host level
with no action from the guest OS other than calling VSS during an application-
consistent recovery-point creation.) The guest-based replication uses an in-guest
agent (known as the Mobility Service) that utilizes a disk driver that sits under the
filesystem but above the volume manager, and it fractures any writes that pass
through so that the write continues down to the volume manager but also is sent to a
process server that collects the writes and sends them to a master target (which is a
service in Azure), which then sends those writes to an attached VHD for each