> Currently all hard drive/SSD manufacturers guarantee that 512 byte sector writes are atomic. As such, failure to write the 106 byte header is not something we account for in current LMDB releases. Also, failures of this type should result in ECC errors in the disk sector - it should be impossible to successfully read a sector that was written incorrectly in the ways you describe.

Even in extreme cases, the probability of failure to write the leading 128 out of 512 bytes of a sector is nearly nil - even on very old hard drives, before 512-byte sector write guarantees. We would have to go back nearly 30 years to find such a device, e.g.

https://archive.org/details/bitsavers_quantumQuaroductManual...

Page 23, Section 2.1 "No damage or loss of data will occur if power is applied or removed during drive operation, except that data may be lost in the sector being written at the time of power loss."

  From the specs on page 15, the data transfer rate to/from the platters is
 1.25MB/sec, so the time to write one full sector is 0.4096ms; the time to
 write the leading 128 bytes of the sector is thus 1/4 of that: 0.10ms. You
 would have to be very very unlucky to have a power failure hit the drive
 within this .1ms window of time. Fast-forward to present day and it's simply
 not an issue.