Hi
Q1/ I tried to launch my local setup, that used to work fine, but now when I launch my local setup I get the "Error establishing a database connection"
I’ve got only One site
I had 1.4.2 Mac , I upgraded it to 2.0.2 but still same issue,
then had a look at this post : Error Connecting to Database,
and when under SSH I launched “service mysql restart” I got same error "…failed!"
I tried to add recovery “innodb_force_recovery = 1” into etc/mysql/my.cnf as stated in your post
re-launched “service mysql restart” I got same error “…failed!”
Q2/ in order to save correctly my site, I should stop my site and then save it ? or my site can run and be fully saved (files+mysql) correctly as well ? as I got some backups … but same errors with these backups 
If you can help me ? thank you in advance