Gitlab backup file location (Omnibus installation)

/var/opt/gitlab/backups by default.

https://gitlab.com/gitlab-org/gitlab-ce/blob/a64d0f79173301dd86db073e9b6a329b56554dbd/doc/raketasks/backup_restore.md says that:

This archive will be saved in backup_path (see config/gitlab.yml)

Then https://gitlab.com/gitlab-org/omnibus-gitlab/blob/9e97671d8dee3ea6a7bbb99347ad279b65689f28/files/gitlab-cookbooks/gitlab/templates/default/gitlab.yml.erb#L208 says it uses the template variable @backup_path

And https://gitlab.com/gitlab-org/omnibus-gitlab/blob/9e97671d8dee3ea6a7bbb99347ad279b65689f28/files/gitlab-cookbooks/gitlab/attributes/default.rb#L120 says:

default['gitlab']['gitlab-rails']['backup_path'] = "/var/opt/gitlab/backups"

I recommend that you clone GitLab omnibus and git grep away for other similar problems, and that you post gitlab questions on SO: it is accepted there and has much greater developer traffic.