Exercise 2: Why a Permission Mismatch Looks Like Corruption — Possible Solution ==================================================================== WHAT THE SYMPTOM ACTUALLY LOOKS LIKE ------------------------------ Per this chapter's table, the diagnostic signal is "'restore succeeded' but the application still can't read or write the restored files." The restore process itself reports no error - the files genuinely exist, in the correct location, with the correct content. From the outside, the application simply not working afterward looks exactly like what you'd expect if the underlying data itself were somehow bad. WHY THIS SUPERFICIALLY RESEMBLES DATA CORRUPTION ------------------------------ Data corruption also typically presents as "the files are there, but something's not working right" - a technician seeing an application fail to function after a restore, with no obvious explanation, has a natural instinct to suspect the data itself is damaged, since that's a common and well-known cause of exactly this kind of downstream failure. WHAT ACTUALLY DISTINGUISHES THE TWO ------------------------------ Corruption is a property of the file's own contents - the data itself is wrong or unreadable in a way that would be true regardless of who or what tries to access it. A permission mismatch is a property of the relationship between the restoring account and the file's own access controls - the data is completely intact and correct, but the account or process that needs to read or write it hasn't been granted the matching permissions, per this chapter, because "the restoring account's permissions don't match what's needed." The problem sits entirely in the access layer, not in the data itself. WHY THE DISTINCTION MATTERS PRACTICALLY ------------------------------ Confusing the two leads to wasted effort in the wrong direction - treating a permission issue as data corruption might lead someone to attempt a fresh restore from a different backup (which would fail identically, since the actual data was never the problem), rather than simply correcting file ownership or access rights on the files already successfully restored. WHY THIS WORKS AS AN ANSWER ------------------------------ It explains what the symptom looks like on the surface, explains why that surface appearance resembles corruption, and explains the actual underlying difference - a data-level problem versus an access-level problem - along with why getting the distinction right changes what the correct fix actually is.