Exchange MTA Status Test
The Exchange MTA (Message Transfer Agent) is a core component of Exchange Server 2000/2003 and is responsible for all non-SMTP message transfer. This includes message transfer to external X.400 messaging systems and Exchange servers connected through X.400 connectors. Message transfer to non-Exchange messaging systems, such as Lotus Notes and Domino or Microsoft Exchange Connector for Novell GroupWise, is controlled by the Exchange MTA through MAPI-based connectors, such as Microsoft Exchange Connector for Lotus Notes or Microsoft Exchange Connector for Novell GroupWise. Exchange MTA is also responsible for remote procedure call (RPC)-based communication with Exchange Server 5.5.
A healthy MTA is key to the error-free transmission of messages across MTAs. Any deterioration in the processing ability of the MTA could therefore result in slower delivery or even non-delivery of critical messages, longer outstanding message queues, and consequently, an inefficient mail server. The ExchangeMtaStatus test monitors the status of an Exchange server's MTA and proactively alerts administrators of abnormalities (if any) in MTA-related operations, so that issues can be resolved quickly and the MTA can resume functioning normally in no time.
Target of the test : An Exchange server 2000/2003
Agent deploying the test : An internal agent
Outputs of the test : One set of results for every Exchange server being monitored.
| Parameters | Description |
|---|---|
|
Test Period |
How often should the test be executed. |
|
Host |
The IP address of the machine where the Exchange Server is installed. |
|
Port |
The port number through which the Exchange server communicates. |
|
IsPassive |
If the value chosen is Yes, then the Exchange server under consideration is a passive server in an Exchange cluster. No alerts will be generated if the server is not running. Measures will be reported as "Not applicable" by the agent if the server is not up. |
| Measurement | Description | Measurement Unit | Interpretation |
|---|---|---|---|
|
Mta associations |
Indicates the number of open associations that this MTA currently has to other MTAs. |
Number |
|
|
Messages/sec handled by an MTA |
Indicates 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 to MTA |
Indicates 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 |
Indicates the number of free buffer elements currently in the MTA pool. |
Number |
|
|
Free headers in the MTA |
Indicates the number of free buffer headers currently in the MTA pool. |
Number |
|
|
Threads in use in MTA |
Indicates the number of threads currently in use by the MTA. |
Number |
This number can be used to determine whether additional processors might be beneficial. |
|
Work queue length in MTA |
Indicates 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 |
Indicates 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 |
Indicates 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 |
Indicates the rate at which data is received over a XAPI connection. |
KB/Sec |
|
|
XAPI transmit rate |
Indicates the rate at which data is transmitted over a XAPI connection. |
KB/Sec |
|
|
TCP data receive rate in MTA |
Indicates 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 data transmit rate from MTA |
Indicates the rate at which data is transmitted over a TCP/IP connection. |
KB/Sec |
|
|
X25 receive rate |
Indicates 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 |
