External drives · Caring for a drive
Is it bad to move or bump an external hard drive while it's running?
Short answer: Yes — a hard disk's moving parts can be damaged by knocks while it runs. Keep it on a stable surface and eject before moving it. SSDs tolerate movement far better. After a drop, copy important files off and run First Aid.
Yes, avoid it. A hard disk has spinning platters and a read head flying just above them, so a knock while it's running can damage it. Put it on a stable surface, and eject it and wait for it to stop before moving it. SSDs have no moving parts and cope with movement far better.
If a hard disk was dropped, copy your important files off it as soon as it mounts and run First Aid. Unusual noises, slow reads or files that won't open afterwards are signs of damage — see why a hard drive clicks or beeps.