Sherman Hayes

I’m Sherman. I work on storage and database infrastructure in Minneapolis, and I write things down here so I only have to work them out once.

Recent

June 18, 2026storage
The fsync You Didn't Call
A successful write() means almost nothing. Here is the rest of the path, including the directory entry that everyone forgets.
May 2, 2026incidentreliability
A Retry Storm, Start to Finish
A downstream service got 200 ms slower. Twenty minutes later we were sending it four times our normal traffic.
March 11, 2026latencymeasurement
p99 Is Lying to You
Your load generator waits for a response before sending the next request. That single fact deletes the worst latency from your data.
February 7, 2026not software
Winter Bike Commuting, Year Six
Studded tires, three layers, and the one piece of advice that actually matters: it's your hands.
January 14, 2026postgres
Autovacuum Is Not Optional
The table was 41 GB holding 3 GB of live rows. Autovacuum had been running the whole time. It had simply never finished.