DT Connections Test

Protecting specific data consists of two main tasks - creating a replication set (to identify the data to protect) and connecting that replication set to a target. A unique connection ID is associated with each target a replication set connects to. The connection ID provides a reference point for each connection. The connection ID is determined by sequential numbers starting at one (1). Each time a connection is established, the ID counter is incremented. It is reset back to one each time the Double- Take service is restarted. For example, if the Double-Take service was started and the same replication set was connected to five target machines, each connection would have a unique connection ID from 1 to 5.

This test monitors the current state of each Double-Take Availability connection and reports and reports the level of activity on each connection, so that the busiest/overloaded connections are revealed, and the operation (mirroring/replication) that is causing the overload can be identified.

Target of the test : A Double-Take Availability server

Agent deploying the test : A remote agent

Outputs of the test : One set of results for each Double-Take Availability connection being monitored.

Configurable parameters for the test
Parameter Description

Test Period

How often should the test be executed.


The IP address of the host for which this test is to be configured.


The port at which the monitored target exposes its SNMP MIB; The default value is 161.


By default, the eG agent supports SNMP version 1. Accordingly, the default selection in the SNMPversion list is v1. However, if a different SNMP framework is in use in your environment, say SNMP v2 or v3, then select the corresponding option from this list.


The SNMP community name that the test uses to communicate with the firewall. This parameter is specific to SNMP v1 and v2 only. Therefore, if the SNMPVersion chosen is v3, then this parameter will not appear.


This parameter appears only when v3 is selected as the SNMPVersion. SNMP version 3 (SNMPv3) is an extensible SNMP Framework which supplements the SNMPv2 Framework, by additionally supporting message security, access control, and remote SNMP configuration capabilities. To extract performance statistics from the MIB using the highly secure SNMP v3 protocol, the eG agent has to be configured with the required access privileges – in other words, the eG agent should connect to the MIB using the credentials of a user with access permissions to be MIB. Therefore, specify the name of such a user against this parameter. 


This parameter appears only when v3 is selected as the SNMPVersion. An SNMP context is a collection of management information accessible by an SNMP entity. An item of management information may exist in more than one context and an SNMP entity potentially has access to many contexts. A context is identified by the SNMPEngineID value of the entity hosting the management information (also called a contextEngineID) and a context name that identifies the specific context (also called a contextName). If the Username provided is associated with a context name, then the eG agent will be able to poll the MIB and collect metrics only if it is configured with the context name as well. In such cases therefore, specify the context name of the Username in the Context text box.  By default, this parameter is set to none.


Specify the password that corresponds to the above-mentioned Username. This parameter once again appears only if the SNMPversion selected is v3.

Confirm Password

Confirm the AuthPass by retyping it here.


This parameter too appears only if v3 is selected as the SNMPversion. From the AuthType list box, choose the authentication algorithm using which SNMP v3 converts the specified username and password into a 32-bit format to ensure security of SNMP transactions. You can choose between the following options:

  • MD5 - Message Digest Algorithm
  • SHA - Secure Hash Algorithm
  • SHA224 - Secure Hash Algorithm 224 bit
  • SHA256 - Secure Hash Algorithm 256 bit
  • SHA384 - Secure Hash Algorithm 384 bit
  • SHA512 - Secure Hash Algorithm 512 bit


This flag appears only when v3 is selected as the SNMPversion. By default, the eG agent does not encrypt SNMP requests. Accordingly, the this flag is set to No by default. To ensure that SNMP requests sent by the eG agent are encrypted, select the Yes option. 


If the EncryptFlag is set to Yes, then you will have to mention the encryption type by selecting an option from the EncryptType list. SNMP v3 supports the following encryption types:

  • DES - Data Encryption Standard
  • 3DES - Triple Data Encryption Standard
  • AES - Advanced Encryption Standard
  • AES128 - Advanced Encryption Standard 128 bit
  • AES192 - Advanced Encryption Standard 192 bit
  • AES256 - Advanced Encryption Standard 256 bit


Specify the encryption password here.

Confirm Password

Confirm the encryption password by retyping it here.


Specify the duration (in seconds) within which the SNMP query executed by this test should time out in this text box. The default is 10 seconds.

Data Over TCP

By default, in an IT environment, all data transmission occurs over UDP. Some environments however, may be specifically configured to offload a fraction of the data traffic – for instance, certain types of data traffic or traffic pertaining to specific components – to other protocols like TCP, so as to prevent UDP overloads. In such environments, you can instruct the eG agent to conduct the SNMP data traffic related to the monitored target over TCP (and not UDP). For this, set this flag to Yes. By default, this flag is set to No.


This parameter appears only when v3 is selected as the SNMPVersion. Sometimes, the test may not report metrics when AES192 or AES256 is chosen as the Encryption type. To ensure that the test report metrics consistently, administrators need to set this flag to Yes. By default, this parameter is set to No.

Measurements made by the test
Measurement Description Measurement Unit Interpretation

Connection activity

Indicates the  amount of time this connection has been active.


A very high value for this measure could indicate that the data is taking too long to be transmitted to the target. 

Connection state

Indicates the current state of this connection. 


The values reported by this measure, their description, and the numeric values that correspond to them have been discussed in the table below:

Measure Value Numeric Value Measure Description
conError 0 A transmission error has occurred. Possible errors include a broken physical line or a failed target service.
conActive 1 Indicates that the connection is functioning normally and has no scheduling restrictions imposed on it at this time. (There may be restrictions, but it is currently in a state that allows it to transmit.)
conPaused 2 Indicates a connection that has been paused. This implies that the network connection exists and is available for data transmission, but the replication and mirror data is being held in a queue and is not being transmitted to the target.
conScheduled 3 indicates a connection that is not currently transmitting due to scheduling restrictions (bandwidth limitations, time frame limitations, and so on).
conNone 4 Indicates that a connection has not been established.


Ops in Retransmit Queue

Indicates the number of operations (create, modify, or delete) currently in the retransmit queue on the source.



Ops Awaiting Acknowledgments

Indicates the number of of operations currently waiting in the acknowledgment queue.


Each operation that is generated receives an acknowledgment from the target after that operation has been received by the target. This statistic indicates the number of operations that are yet to receive acknowledgment of receipt.

Replication Ops Queued

Indicates the number of replication operations currently waiting to be executed on the target.


Replication is the real-time transmission of file changes to a target. These changes, instead of being replicated to a target, may be queued to disk, if a locked file on the target prevents the changes from being written to it, or if a file on the source changes faster than can be transmitted to the target.  Typically, if the system memory allocated to queueing is utilized fully, then new file changes that are to be replicated to a target will be directly queued to disk, while old changes remain in the system memory. Data queued to disk is written to a transaction log.

The value of this measure indicates the number of file changes that are in queue, and are yet to be replicated to the target. A high value of this measure may indicate that too many file changes are awaiting processing or that one/more files on the target have been locked for too long a time.

Mirror Ops Queued

Indicates the number of mirroring operations currently in queue.


Mirroring is the process of transmitting user-specified data from the source to the target, so that an identical copy of data exists on the target. When Double-Take Availability initially performs mirroring, it copies all of the selected data, including file attributes and permissions. Mirroring creates a foundation upon which Double-Take Availability can efficiently update the target server by replicating only file changes.

A high value of this measure indicates that many mirroring operations are pending processing, which could hint at a probable processing bottleneck.

Replication Ops Queued Data

Represents the amount of data that was associated with the queued replication operations during the last measurement period.



Mirror Ops Queued Data

Represents the amount of data that was associated with the queued mirror  operations during the last measurement period.



Operations Transmitted

Indicates the total number of operations that are currently transmitted to the target.



Data Sent

Indicates the total number of bytes sent to the target since the last measurement period.



Operations Received

Indicates the total number of operations (create, modify, or delete) currently received from the target.



Data Received

Indicates the total number of bytes received from the target during the last measurement period.



Resent operations

Indicates the number of operations that were resent because they were not acknowledged.