If you would like to get information regarding what exact database engine Plesk Panel is using, what database name is used by Plesk Panel or where does Plesk stores its backup by default you can check this information in Registry:
Useful keys and parameters:
DUMP_D - directory that Plesk Panel uses by default for storing backups
DumpTempDir - directory that is used for storing temporary backup files or migration data
HTTPD_VHOSTS_D - directory used for storing domain data. Can be also checked by using environmental variable %plesk_vhosts%
PLESK_DATABASE_PROVIDER_NAME - what database engine is used by Plesk Panel for work (Jet, MSSQL, MySQL)
PLESKCP_PROVIDER_NAME - can be iis or apache. This show us what provider is used for Plesk Panel itself. Domains always work on IIS.
PRODUCT_FULLVERSION and PRODUCT_VERSION show us what exact version of Plesk Panel is installed.
Do not try to modify any of these settings manually. That might cause unexpected behavior in Plesk Panel work.