Images first, commands laterBefore any tool is pointed at them, MDF, NDF, LDF, EDB and every log receive read-only forensic copies. Engines write hard during a 'repair', so it is the copy that keeps each following step reversible.
The switch that throws data awaySQL's REPAIR_ALLOW_DATA_LOSS is unusually candid about itself: it reaches consistency by binning whatever it cannot reconcile. If we use it at all, it comes last and only on a copy — never as an opening move.
Ask Exchange politely to begin withA built-in check reads an EDB header without altering a single byte — shutdown state, the range of logs required, how far the damage goes. Its destructive relative, the hard repair, drops pages it cannot read and forces migrations afterwards. Look before you cut, every time.
The truth lies in the storageMost so-called database corruption is really a storage incident in disguise — a RAID member dropped, mains lost mid-flush, a snapshot that went wrong. Straightening the furniture is pointless while the floor is unsound, which is why our server page sits right beside this one.