More compelling alternative to the cylinder icon to illustrate a database for end-users?

Answer 1

I believe the cylinder derives from the idea of a HDD or a stack of platters.

For non-technical users, maybe a picture of a computer or filing cabinets would be more understandable.

Answer 2

Perhaps several images could be layered - an image, a list, an internet icon - to suggest the contents of a database.

Answer 3

I would consider what the user is going to have in the database, if the client is going to use it for photos, maybe make it a stack of Polaroids, or a photo album, really the idea of the cylinder is like a hard disk, but the conceptual idea of a database can relate to whatever will be stored in it.

Be as descriptive as you can for you clients to know what they might find there.