Q: What is InMage Scout?
A: InMage Scout is a recent Microoft acquisition that's being integrated into Azure Site Recovery as another available channel to enable replication and ultimately disaster recovery for additional workloads. InMage Scout uses an agent/monitor running within the source OS that needs to be replicated. The agent captures all write-to-disk actions while in the OS's memory and then fractures the write request to also send to the local InMage Scout Process Server, after which the write continues to disk. Capturing the write in memory and sending it to another system minimizes any additional overhead on the source OS.
The InMage Scout Process Server does all the heavy lifting related to compressing, deduplicating, and encrypting the data, which it then sends over the network to its reciprocal server at the target location, the InMage Scout Master Target Server. This sending of the data is done near-synchronously, which means it isn't done at the same time the write occurs on the local disk—which would affect the performance of the primary workload—but it also isn't sent at some scheduled interval such as every 5 minutes. Instead, the data is sent as quickly as possible, which means perhaps a second of latency depending on network conditions.
When the InMage Scout Master Target Server receives the data, it then performs the writes to the target replica storage. The way this works is the Master Target is a virtual machine (VM); the disks for all the target replica VMs are attached to this Master Target VM, enabling it to perform all the required disk writes. In the event of an actual failover, those virtual disks are disconnect from the Master Target Server and attached to the actual replica VMs, which are then started. The actual target VMs aren't running during regular replication (because the disks aren't even attached to the target VMs during the normal replication). There's also an InMage Scout Configuration Server that provides a centralized management point for the entire solution and the point of entry for management/failover operations.
The InMage Scout Process Server runs on Windows Server 2012 and can run as a physical or virtual instance. A physical instance is typically used for larger-scale environments. The InMage Scout Master Target Server is always a VM because it needs to have the virtual hard drives attached for all the VMs that are actually being replicated to. When replicating to Azure, the InMage Scout Master Target Server is an Azure IaaS VM that still gets attached to the disks for the replica VMs.
Both Windows and Linux are supported. Because the agent runs within the OS being replicated, that OS can be a physical or virtual instance. The replication process is completely independent of any hardware or hypervisor.