No database session was available to satisfy a request on database “{name}”. The number of sessions configured via the Active Directory attribute msExchESEParamMaxSessions on the storage group may be set too low for the level of activity on this storage group. The current value for this parameter is {value}.

Details
Product:	Exchange
Event ID:	1164
Source:	MSExchangeIS Mailbox Store
Version:	6.0
Component:	Information Store
Symbolic Name:	msgidNoFreeJsesPrivate
Message:	No database session was available to satisfy a request on database “{name}”. The number of sessions configured via the Active Directory attribute msExchESEParamMaxSessions on the storage group may be set too low for the level of activity on this storage group. The current value for this parameter is {value}.

Explanation
If the parameter msExchESEParamMaxSessions is not present in Active Directory, then it is calculated from the following attributes on the Information Store object:msExchMaxPoolThreads (default value 4)msExchMaxThreads (default value 100)msExchBackgroundThreads (default value 57)The number of sessions configured is: msExchMaxPoolThreadsnumber of processors)+msExchBackgroundThreads+(msExchMaxThreads3/4).

User Action
Adjust these attributes to increase the number of available database sessions.