Principal Software Engineer

Microsoft • Redmond, WA

5d • $165,600 - $331,200

About The Position

High Availability (HA) is one of the foundational engineering teams in Microsoft 365 Core, owning backend data platform that powers Copilot and storing exabytes of customer sharded data across a globally distributed fleet. We build and own technology that deliver 99.995% availability, enable sub-5-second cross-regional failovers, and safeguard exabytes of customer data. Our team owns database engine (Extensible Storage Engine - ESE), failover cluster, and asynchronous active-passive replication, and all of that is encapsulated in a concept of Database Availability Group (DAG).
Charting a multi-year journey to change that - to disaggregate storage from compute, replace full-replica redundancy with erasure coding, and evolve High Availability from "another hot copy" into an efficient property of a shared storage fabric. We are looking for a Principal Software Engineer to provide the technical leadership and hands-on contribution for this transformation: someone who can hold both the incremental, ship-this-year evolution of the current DAG model and the long-horizon disaggregated-fabric architecture in their head at once and drive the fleet from one to the other without ever compromising durability or availability.
This is a rare opportunity to re-architect a foundational storage system at a scale very few engineers ever touch, with a direct, measurable impact on the cost and efficiency of M365.
Microsoft’s mission is to empower every person and every organization on the planet to achieve more. As employees we come together with a growth mindset, innovate to empower others, and collaborate to realize our shared goals. Each day we build on our values of respect, integrity, and accountability to create a culture of inclusion where everyone can thrive at work and beyond.

Requirements

• Bachelor's Degree in Computer Science or related technical field AND 8+ years technical engineering experience with coding in languages including, but not limited to, C, C++, or C# OR equivalent experience.
• Ability to meet Microsoft, customer and/or government security screening requirements are required for this role. These requirements include but are not limited to the following specialized security screenings: Microsoft Cloud Background Check: This position will be required to pass the Microsoft Cloud background check upon hire/transfer and every two years thereafter.

Nice To Haves

• Master's Degree in Computer Science or related technical field AND 12+ years technical engineering experience with coding in languages including, but not limited to, C, C++ or C# OR Bachelor's Degree in Computer Science or related technical field AND 15+ years technical engineering experience with coding in languages including, but not limited to, C, C++ or C# OR equivalent experience.
• Direct experience with erasure coding (Reed-Solomon, LRC/local-reconstruction codes) and the durability/repair/reconstruct trade-offs at scale.
• Experience with storage-compute disaggregation or cloud-database architectures that separate the log/storage tier from compute (e.g., log-as-the-database designs, page-server architectures).
• Familiarity with the underlying hardware and fabric trends: NVMe, RDMA/RoCE, SMR HDD economics, SSD endurance, DPUs/SmartNICs.
• Background in capacity, performance modeling, or fleet efficiency for exabyte-scale services.
• Experience designing or evolving high-availability database and/or distributed storage engines in production.

Responsibilities

• Own the multi-year technical strategy and architecture for Substrate High Availability and storage disaggregation — spanning the incremental evolution of the current DAG/log-shipping model, a fleet-scale disaggregated erasure-coded storage service, and the longer-term fabric-native direction.
• Drive concrete, shippable efficiency wins on the existing fleet: reducing full-copy redundancy, introducing erasure coding (e.g., LRC/VLRC) for durability at a fraction of the footprint, and decoupling compute placement from data placement.
• Lead the design of the storage data path and control plane: append-only extents, page mapping and garbage collection, metadata/placement services, and the erasure-coding and repair pipeline.
• Reason rigorously about reliability of the engine, efficiency across storage, memory, and CPU simultaneously, netting out what a change saves against what it adds (reconstruct cost, write amplification, network hops), and grounding decisions in measured fleet data.
• Leverage AI and intelligent automation to transform service operations through predictive analytics, autonomous remediation, and Copilot-powered engineering workflows.
• Partner with architects and engineering leaders across Storage Fabric, M365 Core, and Azure infrastructure teams to design innovative solutions that improve availability, durability, performance, and operational efficiency for exabyte-scale storage systems.

Benefits

• The typical base pay range for this role across the U.S. is USD $165,600 - $296,400 per year. There is a different range applicable to specific work locations, within the San Francisco Bay area and New York City metropolitan area, and the base pay range for this role in those locations is USD $220,800 - $331,200 per year.
• Certain roles may be eligible for benefits and other compensation.
• This position will be open for a minimum of 5 days, with applications accepted on an ongoing basis until the position is filled.

What This Job Offers

• Job Type: Full-time
• Career Level: Principal