Customer will upgrade CA Single Sign-On 12.8 sp1 to CA Single Sign-On 12.8 sp3 by “In-Place Upgrade”.
They want their production will NOT be stopped during the upgrade.
However, the docops “Upgrade Policy Store” has the step of "Restart all Policy Servers."
Upgrade Policy Store
Restart all Policy Servers
Complete the policy store upgrade by restarting all Policy Servers that are communicating with the policy store.
Release : 12.8.03
Component : SITEMINDER FEDERATION SECURITY SERVICES
The documentation is correct. However, the only outage should occur when restarting the policy server(s).
Thus, consider that the upgrade will be done when user request volume will be low.