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Linuxstorage

Storage caching in the Linux 3.9 era

Kernel writeback changes show up as MySQL stalls, not neat SQL errors.

For DBAs, Linux 3.9-era storage work mattered where it touched dirty-page writeback and block paths under InnoDB — not every LKML headline.

Practice

  1. Record kernel version in every performance incident
  2. Capture iostat / vmstat beside InnoDB semaphore waits
  3. Soak kernel bumps on a replica before primary fleet

InnoDB assumes fsync means what the stack promises. Writeback regressions appear as stall charts. Know when a “harmless” distro kernel bump moved the ground under the buffer pool.