When I create Stack from the template specifying "device_name"(device path) in "block_device_mapping", the different device path has been configured.
In the region where the maintenance listed in the below "News" page has been completed, the optimal value is automatically configured for the device path. Therefore, there is a possibility that the device path is differently configured from the one you specified.
In future, when you create a template, please do not specify "device_name" in "block_device_mapping"(if you do it, it will be ignored).
News - Virtual Server/Image Storage maintenance in Japan regions (JP1, JP2, P4, JP5)
News - Virtual Server/Image Storage maintenance in region (US1, FR1, DE1, UK1, HK1, SG1)
Tutorials - Deployment Manager - Template Examples - ECL::Compute::Server