Checking an archive before you rely on it.
CHECK THE SIZE
Compare against what you expect. A database dump of a few kilobytes where you expect megabytes has failed.
An archive noticeably smaller than the previous one is a warning.
OPEN IT
Extract it on your own computer. A corrupt archive fails here, and you want to know now.
CHECK THE CONTENTS
Is the database file present Are the uploads or media directories present Is the configuration file present Does the file count look plausible
CHECK THE SQL FILE
Open it in a text editor. It should begin with structure definitions and end cleanly.
A file that stops abruptly mid-statement was truncated, usually by a timeout, and will not import completely.
CHECK THE DATE
Confirm it is from when you think. Backup tools sometimes keep serving an old file when new ones fail.
THE DEFINITIVE TEST
Restore it to a staging subdomain. Nothing else proves a backup works.
HOW OFTEN
Spot-check monthly, restore-test quarterly.
