MO

Mira Osei

Staff engineer, storage team · Rotterdam

Mira works on the parts of the system that are only interesting when they fail. She writes mostly about migrations, on-call practice, and why the boring option usually wins.

34

Posts

2021

Writing since

6

Topics

Migrations

A schema migration in four acts

Expand, backfill, contract — and the uncomfortable weeks in between when both shapes have to be true at once.

17 July 2026 · 11 min read

Operations

On-call is a product decision

Every incident that does not page someone is a feature another team will end up building twice, badly.

10 July 2026 · 7 min read

Storage

The cost of a column

Adding one nullable field to a hot table, priced out through storage, index rebuilds and three years of backups.

26 June 2026 · 9 min read

Postmortem

Forty-one minutes in eu-central

A connection pool, a health check and a deploy that was technically correct. The full timeline and what we changed.

02 June 2026 · 14 min read

Practice

Write the runbook first

If you cannot describe how to recover from the failure, you do not understand the feature well enough to ship it.

18 May 2026 · 6 min read