| Measurement |
Description |
Measurement
Unit |
Interpretation |
| Mta_associations |
The number of open associations that this MTA currently has to other MTAs |
Number |
|
| Message_rate |
The rate at which messages are processed by this MTA during the last measurement period |
Messages/Sec |
A consistent dip in this value is a cause for concern, and warrants further investigation. |
| Message_data_rate |
The rate at which message data is processed by this MTA during the last measurement period |
KB/Sec |
This measure again is a good indicator of the processing ability of the MTA. A high value is hence desired. |
| Free_elements |
The number of free buffer elements currently in the MTA pool |
Number |
|
| Free_headers |
The number of free buffer headers currently in the MTA pool |
Number |
|
| Threads_in_use |
The number of threads currently in use by the MTA |
Number |
This number can be used to determine whether additional processors might be beneficial. |
| Queue_length |
The number of outstanding messages currently in the work queue |
Number |
This value represents the number of messages not yet processed to completion by the MTA. A steady increase in this value implies that messages are not being processed as fast as they should be. This is a clear indicator of a bottleneck at the MTA or a malfunctioning connector component. |
| XAPI_gateways |
The number of XAPI gateways connected to the MTA using the XAPI interface |
Number |
To communicate with the Exchange store, the MTA uses an internal API named XAPI, which is a wrapper around MAPI. XAPI gateways handle the message transfer in and out of the message queues in the Exchange store. A single gateway can have multiple XAPI gateway sessions. The XAPI_receive_rate and XAPI_transmit_rate measures serve as effective indicators of the health of the XAPI interface. |
| XAPI_clients |
The number of XAPI clients connected to the MTA using the XAPI interface. A single client can have multiple XAPI client sessions |
Number |
| XAPI_receive_rate |
The rate at which data is received over a XAPI connection |
KB/Sec |
| XAPI_transmit_rate |
The rate at which data is transmitted over a XAPI connection |
KB/Sec |
| TCP_receive_rate |
The rate at which data is received over a TCP/IP connection |
KB/Sec |
The Exchange MTA uses a number of thread pools to handle communication tasks between the various layers of the Open Systems Interconnection (OSI) stack. These thread pools include reliable transfer service (RTS) threads, kernel threads, RPC threads, transport threads, and TCP/IP or X.25 threads. However, the TCP/IP protocol does not fit exactly into the OSI stack. This is because the TCP/IP protocol, although a layered protocol stack, is not OSI- compliant (although most elements of TCP/IP can be mapped to OSI). To support X.400 communication over TCP/IP according to the OSI standard, the Exchange MTA implements a Transport Protocol Class 0 (TP0) interface on top of TCP/IP. The values of these measures indicate the rate at which data is exchanged over the TCP/IP protocol. |
| TCP_transmit_rate |
The rate at which data is transmitted over a TCP/IP connection |
KB/Sec |
| X25_receive_rate |
The rate at which data is received over an X.25 connection |
KB/Sec |
The X.25 protocol is an OSI-compliant protocol designed specifically for wide area network (WAN) connections on packet-switching networks (such as a public X.400 provider). It is the network protocol that operates on top of HDLC so that the local system can communicate with the next node in the X.25 network. The values of these measures reveal the effectiveness of the X.25 protocol. |
| X25_transmit_rate |
The rate at which data is transmitted over an X.25 connection |
KB/Sec |