VMware vSAN ESA (Express Storage Architecture)

 The announcement of the VMware vSAN Express Storage Architecture™ or ESA for short, represents a massive step forward in the capabilities of the solution, and the benefits to our customers.  This has been achieved in a way that is largely transparent to the user, in the same product they are already familiar with.

The vSAN Express Storage Architecture is a new way to process and store data.  It is an optional, alternative architecture in vSAN that is designed to achieve all-new levels of efficiency, scalability, and performance.  The ESA is optimized to exploit the full potential of the very latest in hardware and unlocks new capabilities for our customers.  It is introduced in vSAN 8, and when using ReadyNodes approved for the ESA, can be selected at the time of creating a cluster.  The ESA in vSAN 8 is an alternative to the Original Storage Architecture (OSA) found in all previous editions of vSAN, as well as vSAN 8.

The Express Storage Architecture in vSAN 8 stands on the shoulders of much of the architecture found in OSA included in previous versions of vSAN, and vSAN 8.  vSAN had already solved many of the great challenges associated with distributed storage systems, and we wanted to build off of these capabilities while looking at how best to optimize a data path to reflect the capabilities of today's hardware.

The advances in architecture primarily come from two areas, as illustrated in Figure 2.

• A new patented log-structured file system.  This new layer in the vSAN stack - known as the vSAN LFS - allows vSAN to ingest new data fast and efficiently while preparing the data for a very efficient full stripe write.  The vSAN LFS also allows vSAN to store metadata in a highly efficient and scalable manner.
• An optimized log-structured object manager and data structure.  This layer is a new design built around a new high-performance block engine and key value store that can deliver large write payloads while minimizing the overhead needed for metadata.  The new design was built specifically for the capabilities of the highly efficient upper layers of vSAN to send data to the devices without contention.  It is highly parallel and helps us drive near device-level performance capabilities in the ESA. 

Some of the capabilities of vSAN ESA are as follows:

• The space efficiency of RAID-5/6 erasure coding with the performance of RAID-1 mirroring.
• Adaptive RAID-5 erasure coding for guaranteed space savings on clusters with as few as 3 hosts.
• Storage policy-based data compression offers up to 4x better compression ratios per 4KB data block than the vSAN OSA.
• Encryption that secures data in-flight and at rest with minimal overhead.
• Adaptive network traffic shaping to ensure VM performance is maintained during resynchronizations.
• The lower total cost of ownership (TCO) by removing dedicated cache devices with the flexible architecture using a single tier in vSAN 8.
• Simplified management, and smaller failure domains by removing the construct of disk groups.
• New native scalable snapshots deliver extremely fast and consistent performance.  Achieve backups more quickly through snapshot consolidations that are up to 100x faster.

The vSAN Express Storage Architecture builds on much of what VMware has released that has made vSAN the number one hyperconverged solution on the market.