Tag Archives: architecture

Behind the Scenes: Architecting HC3

Like any other solution vendor, at Scale Computing we are often asked what makes our solution unique. In answer to that query, let’s talk about some of the technical foundation and internal architecture of HC3 and our approach to hyperconvergence.

The Whole Enchilada

With HC3, we own the entire software stack which includes storage, virtualization, backup/DR, and management. Owning the stack is important because it means we have no technology barriers based on access to other vendor technologies to develop the solution. This allows us to build the storage system, hypervisor, backup/DR tools, and management tools that work together in the best way possible.


At the heart of HC3 is our SCRIBE storage management system. This is a complete storage system developed and built in house specifically for use in HC3. Using a storage striping model similar to RAID 10, SCRIBE stripes storage across every disk of every node in a cluster. All storage in the cluster is always part of a single cluster-wide storage pool, requiring no manual configuration. New storage added to the cluster is automatically added to the storage pool. The only aspect of storage that the administrator manages is creation of virtual disks for VMs.

The ease of use of HC3 storage is not even the best part. What is really worth talking about is how the virtual disks for VMs on HC3 are accessing storage blocks from SCRIBE as if it were direct attached storage to be consumed on a physical server–with no layered storage protocols. There is no iSCSI, no NFS, no SMB or CIFS, no VMFS, or any other protocol or file system. There is also no need in SCRIBE for any virtual storage appliance (VSA) VMs that are notorious resource hogs. The file system laid down by the guest OS in the VM is the only file system in the stack because SCRIBE is not a file system; SCRIBE is a block engine. The absence of these storage protocols that would exist between VMs and virtual disks in other virtualization systems means the I/O paths in HC3 are greatly simplified and thus more efficient.

Without our ownership of both the storage and hypervisor by creating our own SCRIBE storage management system there is no storage layer that would have allowed us to achieve this level of efficient integration with the hypervisor.


Luckily we did not need to completely reinvent virtualization, but were able to base our own HyperCore hypervisor on industry-trusted, open-source KVM. Having complete control over our KVM-based hypervisor not only allowed us to tightly embed the storage with the hypervisor, but also allowed us to implement our own set of hypervisor features to complete the solution.

One of the ways we were able to improve upon existing standard virtualization features was through our thin cloning capability. We were able to take the advantages of linked cloning which was a common feature of virtualization in other hypervisors, but eliminate the disadvantages of the parent/child dependency. Our thin clones are just as efficient as linked clones but are not vulnerable to issues of dependency with parent VMs.

Ownership of the hypervisor allows us to continue to develop new, more advanced virtualization features as well as giving us complete control over management and security of the solution. One of the most beneficial ways hypervisor ownership has benefited our HC3 customers is in our ability to build in backup and disaster recovery features.


Even more important than our storage efficiency and development ease, our ownership of the hypervisor and storage allows us to implement a variety of backup and replication capabilities to provide a comprehensive disaster recovery solution built into HC3. Efficient, snapshot-based backup and replication is native to all HC3 VMs and allows us to provide our own hosted DRaaS solution for HC3 customers without requiring any additional software.

Our snapshot-based backup/replication comes with a simple, yet very flexible, scheduling mechanism for intervals as small as every 5 minutes. This provides a very low RPO for DR. We were also able to leverage our thin cloning technology to provide quick and easy failover with an equally efficient change-only restore and failback. We are finding more and more of our customers looking to HC3 to replace their legacy third-party backup and DR solutions.


By owning the storage, hypervisor, and backup/DR software, HC3 is able to have a single, unified, web-based management interface for the entire stack. All day-to-day management tasks can be performed from this single interface. The only other interface ever needed is a command line accessed directly on each node for initial cluster configuration during deployment.

The ownership and integration of the entire stack allows for a simple view of both physical and virtual objects within an HC3 system and at-a-glance monitoring. Real-time statistics for disk utilization, CPU utilization, RAM utilization, and IOPS allow administrators to quickly identify resource related issues as they are occurring. Setting up backups and replication and performing failover and failback is also built right into the interface.


Ownership of the entire software stack from the storage to the hypervisor to the features and management allows Scale Computing to fully focus on efficiency and ease of use. We would not be able to have the same levels of streamlined efficiency, automation, and simplicity by trying to integrate third party solutions.

The simplicity, scalability, and availability of HC3 happen because our talented development team has the freedom to reimagine how infrastructure should be done, avoiding inefficiencies found in other vendor solutions that have been dragged along from pre-virtualization technology.