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SQL Anywhere 11.0.1 (Français) » SQL Anywhere Server - Database Administration » Starting and Connecting to Your Database » The database server » Database server options


-tl server option

Sets the period at which to send liveness packets.

{ dbsrv11 | dbeng11 } -tl seconds ...
Applies to

All database servers using TCP/IP.


A liveness packet is sent periodically across a client/server TCP/IP communications protocol to confirm that a connection is intact. If the server runs for a LivenessTimeout period (default 2 minutes) without detecting a liveness packet on a connection, the communication is severed, and the server drops the connection associated with that client. Unix non-threaded clients and TDS connections do not do liveness checking.

The -tl option on the server sets the LivenessTimeout value for all clients that do not specify a liveness period.

Liveness packets are sent when a connection hasn't sent any packets for between one third and two thirds of the LivenessTimeout value.

When there are more than 200 connections, the server automatically calculates a higher LivenessTimeout value based on the stated LivenessTimeout value, so the server can handle a large number of connections more efficiently. Liveness packets are sent between one third and two thirds of the LivenessTimeout on each idle connection. Large numbers of liveness packets aren't sent at the same time. If liveness packets take a long time to send (depending on the network, the computer's hardware, and the CPU and network load on the computer), it is possible that liveness packets will sent after two thirds of the LivenessTimeout. A warning appears in the database server message log if the liveness sends take a long time. If this warning occurs, consider increasing the LivenessTimeout value.

Although it isn't generally recommended, you can disable liveness by specifying the following:

dbsrv11 -tl 0

Rather than disabling the LivenessTimeout option, consider increasing the value to 1 hour as follows:

dbsrv11 -tl 3600
See also