Best way to backup and restore the databases of a Drupal 7 multisite using Drush?
This is how I do the restore on a site-by-site basis:

drush @site1 sql-drop -y &amp;&amp; gunzip -c /path/to/backup/file1 | drush @site1 sql-cli


You could maintain a list of site aliases to database name and write a shell script to automate the process.

The database name for an individual site could be extracted as follows:

drush status @site1 --fields=db-name --field-labels=0


Unfortunately, there's no all-in-one solution for restore.

An alternate solution would be to use the Backup and Migrate module, which has drush integration. There are bam-backup and bam-restore commands which might be easier to work with.

As @Duncanmoo mentioned, it's also good to run drush rebuild-registry after the restore.