When VMware unveiled vSAN in March 2014, it wasn’t just another update. It was the beginning of a revolution in data storage. The idea was simple but powerful: connect disk resources directly to the hypervisor and get rid of expensive, complicated arrays. This innovation not only cut costs by 30-50%, but practically defined the era of hypervisor infrastructure (HCI). By 2021, vSAN already had more than 40,000 customers and controlled 41.5% of the market. Finally, virtualization administrators were able to manage storage without having to be experts in traditional storage, which had been a pain in the three-tier architecture for decades.
Genesis of the project: when infrastructure became too complicated
Why was vSAN created at all? Before its era, IT infrastructure was… complicated. It resembled a maze, with administrators juggling separate arrays, dedicated Fibre Channel networks and the compute layer itself. VMware saw the crux of the problem: server virtualization was already everywhere, but traditional arrays were lagging behind. They were becoming bottlenecks, and their closed nature was generating astronomical costs.
By 2012, VMware had more than half a million vSphere customers. At the same time, x86 servers were becoming more powerful, full of local SSDs and HDDs that often lay fallow. This clash between the power of servers and the complexity of storage created the perfect breeding ground for innovation.
The motivation for VMware was threefold. First, it needed to encapsulate the Software-Defined Data Center (SDDC) vision that Pat Gelsinger announced shortly after taking the helm in 2012. They already had vSphere (compute) and were working on NSX (networking), but the third pillar was missing: storage. Second, market pressure. Startups like Nutanix and SimpliVity showed that HCI was in gigantic demand. Third, economics. Customers were tired of paying for expensive, complicated arrays and wanted to manage everything from one place.
As Gelsinger put it at VMworld 2013: “We believe the next big area of innovation is software-defined storage.” It wasn’t just marketing. Gartner estimated that 26% of IT budgets were consumed by storage alone. It was time to change that.
Birth of the technology: from announcement to product
The vSAN story began more quietly, however. Back in 2011, VMware released the vSphere Storage Appliance (VSA) – a solution that didn’t win the market, but showed the company’s ambition. The real breakthrough came at VMworld 2012 in San Francisco. During a technical session on “Software Defined Storage,” Christos Karamanolis and Kiran Madnani showed an early version of the technology, then known as “VSAN” or “VMware Distributed Storage.” They clearly stated: “THIS IS A TECH PREVIEW, with no guarantees if or when we will release it.”
But Duncan Epping, already an influential figure in the community, immediately captured the gist: “This solution is built directly into the hypervisor. That’s the main differentiator… it’s not a virtual machine or an appliance!”
A year later, on August 26, 2013, Pat Gelsinger officially announced VMware Virtual SAN (VSAN). That same day, Duncan Epping and Cormac Hogan – key evangelists for the technology – set out to educate the community on their blogs. The market responded instantly. The beta program attracted more than 12,000 participants, an unprecedented number at VMware. This showed how much the industry had been waiting for such a solution. After six months of intensive testing, on March 12, 2014, vSAN 5.5 (lower numbers were strategically omitted to show maturity) officially hit the market.
The architectural revolution: what vSAN did differently
What exactly did vSAN do differently? All the magic was in the architecture. It was the first HCI platform integrated directly into a hypervisor kernel, rather than running as a separate virtual machine (Controller VM). This decision had a gigantic impact on performance and simplicity.
Instead of a central array, vSAN aggregated local disks from all ESXi hosts in a cluster, creating a single, shared pool. You added a server – your computing power and capacity grew. This was scalability that traditional SANs could only dream of.
vSAN also abandoned traditional file systems in favor of an object-oriented model. Each VMDK, snapshot or swap file was a separate object, which vSAN divided into components and dispersed across hosts for resiliency. But the real revolution for administrators was policy-based management (SPBM). Instead of manually carving out LUNs, you simply defined what you needed in a policy: “This VM has to survive a two-host failure (FTT=2) and use RAID-6.” vSAN took care of the rest. This could be changed on the fly, without interrupting work.
The original architecture (OSA) was based on two-tiered disk groups: a fast flash drive (SSD/NVMe) served as write cache and storage, and capacitive drives (HDD or SSD) stored data. In 2014, competitors like Nutanix relied on Controller VM, which generated overhead and latency. vSAN, running in the kernel, had full I/O visibility and minimal overhead. It ran on any x86 server with vSAN ReadyNode certification, while others sold closed appliances.
Evolution over a decade: from 5.5 to 8.0 and beyond
vSAN did not rest on its laurels. Its evolution over the past decade has been a series of transformations. It started in 2014 with version 5.5, which only supported hybrids (flash as cache, HDD for capacity). Just a year later, vSAN 6.0 brought all-flash support and doubled the cluster scale to 64 nodes. This was the foundation.
Then came the enterprise-class features. Version 6.1 (2015) introduced key functionality: stretched clusters (clusters stretched between locations) and support for small offices (ROBO). The real breakthrough in efficiency came in vSAN 6.2 (2016): deduplication, compression and redundant encryption (RAID-5/6) allowed customers to reduce data occupancy by 50-70%.
The next few years saw the building of operational maturity. vSAN 6.6 (2017) added native data-at-rest encryption without the need to buy expensive SEDs, and version 6.7 (2018) moved management to a modern HTML5 interface and made admins’ lives easier with integration with vRealize Operations.
In 2020, vSAN entered the cloud and services era. Version 7.0 introduced native file services (NFS and later SMB), eliminating the need to put up separate NASes. There was also HCI Mesh, an ingenious feature that allowed clusters to “borrow” disk space from each other, finally separating compute and storage resources.
But the biggest architectural change came in 2022 with vSAN 8.0. VMware introduced Express Storage Architecture (ESA), an architecture built from scratch for NVMe drives. ESA got rid of traditional disk groups (cache + capacity) in favor of a single NVMe pool. The new proprietary file system (LFS) provided 2-5 times better performance, 8 times better compression and instant snapshots. The latest versions, like vSAN Max (2023), go even further, allowing you to build dedicated storage clusters that support compute clusters, which is ideal for petabyte environments.
Visionary team: the people behind the technology
Behind every great technology are people. vSAN was no exception. It was Pat Gelsinger, taking the helm as CEO in 2012, who set the vision for the SDDC and gave the project the green light. It was engineers like Christos Karamanolis, who presented the first tech preview, and Satyam Vaghani, whose earlier work on VMFS paved the way for vSAN.
But technology is one thing, and adoption is another. This is where Duncan Epping and Cormac Hogan came on the scene. These two tech evangelists have taken on the titanic job of educating the community. With their blogs, sessions at VMworld and the iconic book “vSAN Deep Dive,” they translated the complex architecture into an understandable language for thousands of administrators. Without them, vSAN would not have captured the market so quickly.
Problems that vSAN solved: before and after
To fully appreciate vSAN, one must remember what life was like before it. The traditional IT architecture was a nightmare of complexity. Deploying a new machine required the involvement of three different teams: from servers, from FC networking and from arrays. Provisioning a new LUN took not minutes, but days and sometimes weeks.
Costs? Astronomical. The arrays themselves cost a fortune, plus vendor lock-in and expensive cyclic migrations. Centralized arrays were also performance bottlenecks and single points of failure.
vSAN turned the tables. Management went back to the vSphere administrator – one console, one skill set. Storage deployment time was reduced from days to minutes (customers reported 76% time savings). Costs (TCO) dropped by 30-50% because vSAN ran on regular x86 servers. Instead of buying “stock” for 5 years, you could scale linearly, adding one server at a time. And the performance? Thanks to the architecture running in the kernel and keeping data close to VMs, it was not only higher, but above all predictable.
Industry impact: how vSAN changed the market
vSAN was not just a commercial success – it changed the rules of the game in the entire storage industry. The numbers speak for themselves: from a few hundred customers in 2014 to more than 40,000 today, with control over 41.5% of the HCI market (IDC data from 2021). For five years in a row, Gartner has placed vSAN in the leadership quadrant, praising it for its vision and integration.
More importantly, vSAN has legitimized HCI in the eyes of large corporations. When VMware, the company that manages critical systems at half a million customers, said “HCI is ready for production,” CIOs began to listen. That opened the door for the entire market.
Competitors had to respond. HPE bought SimpliVity, Dell tightened its partnership with VMware on VxRail, and traditional players like NetApp had to adjust their strategies. vSAN has forced the entire industry to compete not only on features, but especially on total cost of ownership (TCO). It has gone from a solution for VDI and branch offices to a platform on which more than 60% of customers run their key business applications, such as Oracle, SQL Server and SAP.
Technical foundations: how vSAN combines storage with compute
How does it all work under the hood? The heart of vSAN is integration at the ESXi kernel level. When you enable vSAN, each host commits its local disks to a shared pool.
In the Original Storage Architecture (OSA), the administrator created disk groups: one fast flash drive for cache and 1-7 drives for capacity (HDD or SSD). The write flow was brilliant in its simplicity. The write went to the fast cache disk and was immediately acknowledged – the VM didn’t wait for the data to land on slower disks. The vSAN itself, in the background, moved data to the capacity tier. Reads in the hybrid were cached in the cache, and in all-flash went straight from the capacity layer.
Resiliency was taken care of by distributed RAID algorithms. The FTT=1 (Tolerate One Failure) policy mirrored data (RAID-1) to another host. RAID-5 (3+1) or RAID-6 (4+2) saved space. Small “witness” (witness) objects took care of quorum and prevented “split-brain”.
And since everything was object-oriented, every policy was applied per-VMDK, with vSAN non-stop policing. When a host went down, vSAN automatically rebuilt the missing components on other servers. All this was tied together by a simple Ethernet network (10GbE or more recommended).
The ESA architecture introduced in vSAN 8.0 overturned even this: it got rid of disk groups, put everything on NVMe and a new LFS file system, achieving several times the performance increase on the same hardware.
Summary: a decade of transformation
vSAN has come an incredible way. It started as a bold idea in 2012, and today it is a dominant player in the HCI market with more than 40,000 customers. It was born out of frustration with the complexity and cost of traditional arrays, offering instead simplicity, hypervisor integration and management by policy.
It’s not just a product – it’s a technology that has redefined the market, forced competitors to adapt and proved that software-defined infrastructure is the future. From a simple hybrid in 2014, to key enterprise features like deduplication and encryption, to the revolutionary ESA architecture and disaggregated vSAN Max, it’s been a decade of continuous innovation.
The vSAN story is proof of what happens when vision, engineering and market education come together at the right time.
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