About system components
The product solution includes these components:
• Branch server—One or more branch-side servers that access data from the system instead of a local storage device. These servers can also run as virtual machines (VMs) within the Edge hypervisor node.
• Blockstore—A persistent local cache of storage blocks. Because each Edge is linked to one or more dedicated fileshare exports at the data center, the blockstore is authoritative for both reads and writes. The blockstore on the branch side synchronizes with its exported fileshare(s) at the data center.
• Storage system—One or more branch-side VMware hypervisors with datastores.
• Edge—The branch-side component of the system that links the blockstore through the Core to the storage at the data center. The Edge also includes SteelHead functionality to provide WAN optimization services.
• Data center SteelHead—The data center-side SteelHead peer for WAN optimization.
• Core—The data center component of the product family. The Core manages data transfers between the data storage and the Edge.
At the data center, Core integrates with existing storage systems, virtual infrastructure, and SteelHead deployments. Depending on the deployment, Core connects dedicated storage with each Edge appliance at the branch office.
The branch office server connects to Edge. The Edge also connects to the blockstore, a persistent local cache of storage blocks within the Edge itself. The blockstore is the Edge authoritative persistent cache of storage blocks. The blockstore is local from a branch perspective and holds data from all the exported fileshares available through a specific Edge. The blockstore is authoritative because it includes the latest-written data before it is sent through the Core to a storage array or file server at the data center. When a server at the branch office requests data, that data is served locally from the blockstore if the data is currently present. If it is not present, the Edge retrieves it through the Core from the data center LUN or exported fileshare. Similarly, newly written data is spooled to the local blockstore, acknowledged by the Edge to the branch office server, and then asynchronously propagated to the data center. Because each Edge implementation is linked to one or more exported fileshares at the data center, the blockstore is authoritative for both reads and writes and can tolerate WAN outages without affecting cache coherency.
Blocks are transferred between the Edge and the Core through an internal protocol. The Core then writes the updates to the fileshares exported from the data center file server. The product is designed to be coupled with the SteelHead WAN optimization. You can further optimize traffic between the branch offices and the data center by implementing SteelHeads.
The data cache in the blockstore is stored as-is, and it is not deduplicated. Edge appliances include the SteelHead, and in the data center, the Cores are coupled with SteelHead products, which assist with data reduction and streamlining between the Edge and the Core.