Modifying the size for safety net on Exchange 2013

In this article let's see how to change the values of Safety Net in Exchange 2013.

The Transport Dumpster has been replaced with Safety Net in Exchange 2013. It prevents data loss by maintaining a queue of successfully delivered messages. Unlike the earlier version of transport dumpster it also holds messages of mailboxes that are not a member of a DAG, as well as Public Folder mailboxes.

Exchange 2013 Safety Net does not require the use of a DAG. The Safety Net is no longer a single point of failure, since it has 2 queues: primary safety net and shadow safety net.

Because of this, we will notice huge difference in the log file size compared to the legacy Transport Dumpster in Exchange 2010.

This is because the Safety Net ESE database is holding both the primary Safety Net and shadow Safety Net information in one queue.

Where does this Safety Net Queue location reside?

There is no dedicated Safety Net location in Exchange 2013 and it stores the messages in the same transport queue that is located in the mailbox server.

All the different queues are stored in a single ESE database. By default, this queue database is located on the transport server at %ExchangeInstallPath%TransportRoles\data\Queue.

Below is the location of the safety net queue in Exchange 2013

https://exchangequery.files.wordpress.com/2015/03/transport-queue.png?w=600&h=241

At times there might be a situation where the safety net queue will grow abnormally. Below are the steps that can be followed when we run into these kind of scenarios.

First we can create a new transport queue with the following steps.

On each server with a large mail.queue file:
a. Stop the MSExchangeTransport service.
b. Delete the mail.que file.
c. Start the MSExchangeTransport service.

Also we can troubleshoot Safety Net by changing the Safety Net hold time.

By default the hold period for the Safety Net is 2 days. If you wish to change these values follow the below procedure.

To check the safety net hold time run the below command:
Get-TransportConfig | ft name,Safety*

https://exchangequery.files.wordpress.com/2015/03/transport2.png?w=600&h=211

In order to change the value run the below command:

Set-TransportConfig –SafetyNetHoldTime 1.00:00:00

https://exchangequery.files.wordpress.com/2015/03/transport3.png?w=600&h=237

You will get the above warning once you run the above command, so you need to ensure that the Safety Net hold time is a value less than the replay lag time of any of your lagged database copies, if you are using them. 

There is a value called Message Expiration Timeout. This is the length of time a message in the shadow Safety Net can remain the queue before it expires.

To see this value run the below command:

Get-TransportService |ft name,messageexpiration*

https://exchangequery.files.wordpress.com/2015/03/transport4.png?w=600&h=106

To change this value run the below command:

https://exchangequery.files.wordpress.com/2015/03/transport5.png?w=600&h=18

These values can be changed from the EAC as well.

In order to change the value through EAC perform the following steps:

Open EAC, Click on mail flow tab, Click on receive connectors

Click on the More icon (...) and click on Organizational transport settings

https://exchangequery.files.wordpress.com/2015/03/transporteac.png?w=600&h=116

Below you have the option to change the value of the Safety Net hold time as shown, as well as the Shadow Safety Net hold time, which is indicated by the "Maximum retention time" field.

https://exchangequery.files.wordpress.com/2015/03/transporteac2.png?w=600&h=253

Hope this article will help to change the safety net value in Exchange 2013.