The most important backup you will take.
WHY
A migration touches everything: files, database, DNS, email. Anything can go wrong, and the fallback is the old environment plus a backup.
WHAT TO TAKE
A full account backup from the source, downloaded to your own computer A separate database export A separate copy of email, via IMAP A record of DNS records A record of cron jobs
VERIFY IT BEFORE STARTING
Open the archive. Confirm the database file is present and a plausible size. Confirm the files are there.
A migration is the worst time to discover a backup is incomplete.
KEEP THE OLD ENVIRONMENT
Do not cancel the source hosting until the new one is verified and DNS has fully propagated. A week is a sensible minimum.
The old environment is your real fallback; the backup is the second line.
AFTER MIGRATING
Take a fresh backup on the new server once everything is confirmed working. The migration backup is from the old environment and may not restore cleanly on the new one.
THE RULE
Never cancel anything until the replacement is proven.
