A Modern Storage Fabric

Nutanix AOS (Acropolis Operating System) is the core software foundation of the entire Nutanix Cloud Infrastructure. Its primary job is to create a hyperconverged platform by pooling the compute and local storage (SSDs, HDDs) from all the individual servers (nodes) in a cluster into a single, unified resource pool.

The key difference is their role:

• AOS is the underlying operating system that manages all the storage and data services. It is the intelligence that creates the resilient, scalable infrastructure.

• AHV is the optional, integrated hypervisor that runs on top of AOS to create and manage virtual machines.

You can run different hypervisors on top of AOS (like VMware ESXi or Microsoft Hyper-V), but AOS is always the essential software layer providing the core Nutanix functionality.

The Distributed Storage Fabric (DSF) is the heart of Nutanix AOS. It is the proprietary, software-defined storage technology that aggregates the local storage drives from every node in the cluster and presents it as a single, high-performance, and resilient storage pool to the hypervisor.

Nutanix AOS is built with data resilience as a core principle, using several mechanisms to protect data without relying on traditional RAID.

• Replication Factor (RF): Data is written in multiple copies across different nodes in the cluster. With a standard Replication Factor of 2 (RF2), every piece of data exists on at least two different nodes. If an entire node or disk fails, the data is still immediately available from its replica.

• Self-Healing: If a disk or node fails, AOS automatically detects the failure and begins to re-replicate the missing data copies to other healthy nodes in the cluster to restore the full replication factor. This process happens in the background without administrative intervention.

• Data Integrity Checks: AOS performs checksums on data as it is written and read to protect against silent data corruption and ensure data integrity.

Nutanix AOS includes a suite of enterprise-grade storage optimization features designed to reduce the data footprint and improve performance, which are typically licensed and enabled by default in most tiers. Key features include:

• Compression: AOS can use various compression techniques on data to save space, and it intelligently applies them post-process so as not to impact initial write performance.

• Deduplication: The platform can deduplicate data both inline (as it is written) and post-process, identifying and eliminating redundant copies of data blocks to save significant capacity.

• Erasure Coding (EC-X): Similar to RAID 5/6 but implemented in software, Erasure Coding provides a more space-efficient way of protecting data than just replication. For example, instead of storing three full copies of data (RF3), EC-X can use parity calculations to protect against failures while using much less raw storage capacity.

Nutanix AOS upgrades are designed to be simple, automated, and non-disruptive, using a feature called One-Click Upgrade. The entire process is managed from the Nutanix Prism web console.