DSHR s Blog
Tuesday, March 16, 2021
Correlated Failures
The invaluable statistics published by Backblaze show that, despite being built from technologies close to the physical limits (Heat-Assisted Magnetic Recording, 3D NAND Flash), modern digital storage media are extraordinarily reliable. However, I have long believed that the models that attempt to project the reliability of digital storage
systems from the statistics of
media reliability are wildly optimistic. They ignore foreseeable causes of data loss such as Coronal Mass Ejections and ransomware attacks, which cause
correlated failures among the media in the system. No matter how many they are, if all replicas are destroyed or corrupted the data is irrecoverable.