innodb_force_recovery when InnoDB corruption
According to MySQL's documentation, if you use innodb_force_recovery=1, the server will start even if it detects a corrupt page.

http://dev.mysql.com/doc/refman/5.0/en/forcing-innodb-recovery.html

Still, there are a couple of things you may want to check.  

Are there any relevant errors in mysql's error log?  cat /var/log/mysqld.log

Is the file system OK, can you create files with touch in the same partition ?  ex. touch /var/somefile.txt

If you have a full backup of your databases, as you mention in your question, you can delete the ibdata and ib_logfile(s) and recreate them, then restore your databases.  This will resolve any corruption issues you may have in the innodb files. 

The steps are:


Stop mysql
delete the ibdata and ib_logfile files. 

ex : rm -f /var/lib/mysql/ibdata1

ex : rm -f /var/lib/mysql/ib_logfile*
Start MySQL (which recreates the innodb files)
Restore the dump  mysql -u root -p &lt; mydump.sql


As long as you only delete the innodb files(ibdata and ib_logfiles), your users and their access rights to the databases will still be in tact.