QlikView Server has five Persistent Global Object (PGO) files for storing server side non-application specific data. The list below gives an idea of the content in each file.
BorrowedCalData.pgo contains information about leased licenses (which machine it was leased to, which user and when it was leased). Unless using leased CALs, there should be very little access to this file (and it should be very small).
TicketData.pgo contains issued tickets. When one node authenticates a client it gives it a ticket which can later be used to start a session on any of the other nodes. Those nodes then validate the ticket (by looking in TicketData.pgo) rather than doing an authentication. There are two accesses for each new session (one when the ticket is created and one when it is looked up/consumed).
IniData (all setting.ini s)
IniData.pgo contains the same information as the settings.ini for the QVS, in a different format and synced between the nodes. The nodes will regularly read from the file to see if there are changes (roughly once every 5 seconds), or write their changes if they receive some changed setting from the QMC. Since the file is so small it is usually not a performance issue to do this once every 5 seconds, especially if you only have 2 or 4 nodes.
ServerCounters.pgo contains basic statistics for each node in the cluster, such as DocLoadsSinceMidnight, DocLoadFailsSinceMidnight, SessionStartsYesterday and LastUpdate timestamp to show that the node is still alive. It should be accessed once or twice per minute and contain very little information.
CalData.pgo contains information about allocated and currently used CALs. It is accessed when users open or close a session, or access the AccessPoint. It is also accessed on scheduled events (like once every 10 seconds to check if it is time to throw out any user because the CAL was removed by another node, or once every time the performance log is written).