Managing Performance Thresholds › How Performance Thresholds Work › How Performance Metrics Work › Server Metrics

Server Metrics

Indicate an application performance problem is caused by a server that hosts the application.

Server Response Time

Is the time it takes for a server to send an initial response to a client request or the initial server "think time." Increases in the Server Response Time generally indicate the following:

• A lack of server resources such as CPU, memory, disk, or I/O
• A poorly written application
• A poorly-performing tier in a multi-tier application

Server Connection Time

Is the amount of time that a server takes to acknowledge the initial client connection request by sending a Syn-Ack in response to the client’s SYN packet.

Refused Session Percentage

Is the percentage of connection requests that were explicitly rejected by the server during the three-way handshake A three-way handshake, in the TCP protocol, is used to establish a connection between a client and a server. The SYN packet is sent by the client to a server to initiate the connection setup. A SYN-ACK packet is sent by the server to the client to acknowledge receipt of a SYN from the client. Finally, an ACK packet is sent by the client to the server to acknowledge receipt of a SYN-ACK from the server and to establish the TCP connection. A monitoring device uses the three-way handshake in the timing and analysis of monitored connections on the network.. Part of the Unfulfilled TCP/IP Session Requests report.

Unresponsive Session Percentage

Is the percentage of sessions where a connection request was sent, but the server never responded. Part of Unfulfilled TCP/IP Session Requests report.