By default Trek saves all migrations and database backups in your user/cache folder, but it is recommended to save migrations to a different location. Trek only uses the default user/cache folder because it should be writable as part of ExpressionEngine's default configuration. It is common for 3rd party add-ons to flush the cache, so you want to avoid having your migrations accidently deleted by another add-on. For this reason it is highly suggested to choose another local directory path, or use an Amazon S3 bucket. You can manually relocate your migration files as needed. For example, if after installing Trek some migrations are saved to the user/cache folder, you may want to move them to a directory above the web root. If your public directory is /var/www/html/public, you may want to save migrations to /var/www/html/migrations. To do that, change the storage['local']['path'] value in your config file, then move the migration files to that new folder. The same process may be taken if you decide to add an S3 bucket in the future. If a migration file goes missing, and an error occurs in a remote environment because a query, or group of queries were not executed, BoldMinded can not assist with such errors.