I’ll just put it out there: anyone who’s handed a “move this S3 bucket” task and says it’s easy is either lying or hasn’t tried to keep permissions and metadata intact, not to mention maintain zero downtime. Read @mikeappsreviewer and @codecrafter—they nailed the pros and cons—but let’s cut through the fluff and get into the messier bits.
First, all the AWS DataSync talk is cute (and yes, it works if you like to stay strictly AWS), but IMO, the permissions headache is where people actually trip. Data is easy to move—keeping your bucket policies, ACLs, AND making sure that all the transferred files are owned by the right account in the target bucket? That’s where the AWS “just use --acl bucket-owner-full-control” suggestion falls apart as soon as you hit that one weird object someone uploaded with a unique canned ACL.
For me, here’s how I’d attack a real-world migration (not just a “demo”):
- Prep: Make the bucket in the target account, match all the policies and versioning settings.
- Bulk Copy: Use AWS CLI (
aws s3 sync), but watch out: by default, you might lose old versions or some metadata unless you tweak it. For millions of files? CLI might choke, so DataSync or even an S3 Batch Operation can help. - Permissions: After migration, run a script to compare/list object ACLs and policies, then fix ownership (and logs! Don’t forget logs or you’ll be hunting 403s on Monday).
- Delta Sync: After the cutover, re-sync changed files to catch edits/uploads during migration (yup, it’s always a moving target).
- Switch DNS/endpoints: Then point consumers at the new bucket, and watch your error logs like a hawk.
If you only care about data and zero downtime is a must-have, you could use S3 Replication to parallelize updates and do a final sync at cutover. But S3 Replication needs versioning enabled and cross-account trust. Sometimes, that’s more political than technical.
BTW, CloudMounter (as mentioned) is stellar for ad-hoc moves, small-to-midsize bucket cleanups, or when you want to treat S3 like Dropbox. I still keep it handy for spot-jobs—way less brain damage than remembering AWS CLI flags at 2AM. But trying to copy 10TB through your ISP using CloudMounter? Nah, that’ll make you hate life.
Don’t trust a one-step tool. Double-check your permissions, run object ownership reports, and always compare source/destination with something like aws s3api list-objects. Human error is real. No shame in paranoia!
In short: there is no magic “move S3 bucket with no pain” button. It’s a rough ride, no matter how many scripts or handy desktop apps you throw at it. Brace yourself, verify everything, and keep your caffeine supply ready.