Scaling Writes hard
MySQL's InnoDB engine writes pages to a 'Double Write Buffer' before writing them to the main data files. What specific hardware failure does this prevent?
- A CPU overheating.
- B Network Partition.
- C Deadlocks.
- D Partial Page Writes (Torn Pages): If power fails while writing a 16KB page, only 4KB might reach the disk, corrupting the page. The buffer allows recovery from the backup.
Answer: D. Partial Page Writes (Torn Pages): If power fails while writing a 16KB page, only 4KB might reach the disk, corrupting the page. The buffer allows recovery from the backup.
Hardware sectors (512 bytes) are smaller than DB pages (16KB). A crash mid-write leaves a half-written page. The Double Write buffer ensures a pristine copy exists to restore from during crash recovery.
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