We'd like to get link to documentation about Policy Store
failover. Where can we find it ?

At first glance, you'll find documentation about Policy Store failover
here :

  Policy Server to Policy Store Communication
  https://techdocs.broadcom.com/content/broadcom/techdocs/us/en/ca-enterprise-software/layer7-identity-and-access-management/single-sign-on/12-8/implementing/implementing-ca-single-sign-on/architectural-use-cases.html

  Configure LDAP Storage Options
  https://techdocs.broadcom.com/content/broadcom/techdocs/us/en/ca-enterprise-software/layer7-identity-and-access-management/single-sign-on/12-8/configuring/policy-server-configuration/configure-policy-server-data-storage-options/configure-ldap-storage-options.html

  Policy Server Management Console
  https://techdocs.broadcom.com/content/broadcom/techdocs/us/en/ca-enterprise-software/layer7-identity-and-access-management/single-sign-on/12-8/using/policy-server-management-console.html

About specific question on the internal replication from the Policy
Store vendor, please consult the vendor documentation and / or consult
the vendor support.