Smooth Scaling: System Design for High Traffic

Rebuilding Observability for the Agentic AI Era with Suman Karumuri


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Suman Karumuri has spent 17+ years building observability systems at Amazon, Twitter, Pinterest, Slack, and Airbnb. He was tech lead for Zipkin at Twitter, co-authored the OpenTracing specification that fed into OpenTelemetry, and has now replaced Elasticsearch twice at high-traffic platforms. In this episode of the Smooth Scaling Podcast, Suman walks host Jose Quaresma through KalDB, the open-source, cloud-native log search engine he is building into a product, which runs at petabyte scale at Slack and Airbnb. They get into why he keeps rewriting Elasticsearch instead of tuning it, how separating compute from storage on S3 changes what a log system can do, and the recovery-task trick that keeps fresh logs visible when volume spikes 10x. The back half turns to agentic AI: why agents querying logs in unpredictable bursts break traditional log stacks, why you can't sample data anymore, and what engineering leaders should measure before the bill explodes. A concrete, in-the-weeds look at running log search when the primary user is no longer human.

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  • (00:00) - Intro
  • (01:04) - The origin story of KalDB
  • (05:45) - Why keep the Elasticsearch API
  • (07:09) - Separating compute from storage
  • (11:07) - Solving the 12-hour log lag
  • (14:02) - The journey of a single log message
  • (15:56) - What makes KalDB unique
  • (18:17) - Why not just use ClickHouse?
  • (22:12) - The polystore: search and analytics together
  • (23:38) - Native support for traces
  • (24:27) - How agents change observability
  • (31:24) - Chat as the UI, and what breaks first
  • (35:11) - What engineering leaders should do now
  • (39:54) - Build for a burning problem
  • (41:15) - Rapid fire: Acquired, and "scalability is..."
  • Suman Karumuri is the founder of KalDB, the open-source cloud-native log search engine he is now building into a product. KalDB runs at petabyte scale at Slack, Salesforce, and Airbnb. He spent 17+ years building observability systems at Amazon, Twitter, Pinterest, Slack, and Airbnb, was tech lead for Zipkin at Twitter, and co-authored the OpenTracing specification under the CNCF, which became the foundation of OpenTelemetry. He is based in San Francisco.

    Suman has replaced Elasticsearch twice at high-traffic platforms. And with the rise of Agentic AI querying log systems in non-deterministic bursts, this places a whole new kind of stress on those systems to perform at high scale.


    Suman Karumuri: https://www.linkedin.com/in/mansu/
    Host José Quaresma: https://www.linkedin.com/in/jose-quaresma/ 

    This podcast is produced and researched by Perseu Mandillo, and brought to you by Queue-it, your virtual waiting room partner. 

    © Queue-it, 2026

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