Functional Architecture

Logical Architecture of aSAN

The logical architecture presents aSAN as a single, consolidated storage pool abstracted from the underlying physical disks. It is built on a distributed, scale-out model where each host contributes its local storage (SSDs and HDDs) to the collective pool. This architecture employs a shared-nothing design, meaning there is no single point of failure, and data is intelligently distributed across all nodes to balance load and maximize resource utilization.

Basic aSAN Process

The core operation involves processing I/O requests from virtual machines. When a VM issues a write I/O, the aSAN client on the compute node processes the request, which typically involves breaking the data into shards, creating multiple replicas for redundancy, and distributing these replicas across different nodes in the cluster. This ensures data availability and integrity even in the event of a node or disk failure.

Read I/O Process of VMs

For read operations, aSAN optimizes performance through data localization. Whenever possible, it serves the read request directly from the local replica of the data residing on the same host as the VM, minimizing network latency. If a local replica is unavailable, the system fetches the data from a remote node over the storage network, ensuring uninterrupted data access.