How to migrate from mysql 5.1 to 5.5?

I am just migrating from 5.1 to 5.5. I copy my data from mysql5.1 data forlder to mysql5.5/data.

I just wondered if I can overwrite the file ibdata1 in mysql 5.5 data directory?

Thanks Arman.

EDIT

Yes I can copy 5.1 to 5.5 and th开发者_如何学JAVAen I need to run mysql_upgrade

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Have you visited the MySQL 5.5 FAQ: Migration portion of the reference manual? They have a specific page dedicated to moving from 5.1 to 5.5 with step-by-step guide (including making a backup).