Feature Exploration: Exchange 2013 Transport High Availability

Presented March 11, 2014 at NYExUG MeetingLast Updated on March 11, 2014

Ben SerebinEhlo & Network ConsultantREEF Solutions (www.reefsolutions.com)If you can’t get enough Exchange & technologyread my blog http://blog.reefsolutions.com

* throughout presentation indicates additional information on reference page in back of presentation

About Ben Serebin

• Working in the IT field since 1996 (18 years)

• Specialty is Exchange Server, Spam Filtering, DNS, & complex wireless deployments.

• Upcoming Fun Projects: Working to design Exchange-aware Azure/AWS based Geo Load Balancing, Upgrading network to

10Gb for Hyper-V replication, adding/changing/removing clustered spam filtering across 2 states

• Current Environment: ESXi 4.x & 5.x and Hyper-V 2012 & 2012 R2. Exchange 2007 w/BES 5 and BES 10. Plan to roll out 2013

SP1 DAGs across 2 sites.

Agenda for Presentation

• Why and When?

• History of Transport High Availability

• Transport HA Improvements

• Shadow Redundancy Requirements

• Shadow Redundancy for Any SMTP Server

• Shadow Redundancy Configuration Options

• Shadow Redundancy Work Flow

• Safety Net Overview

• Safety Net Scenarios

• Safety Net Configuration Options

Why and When you would use Transport High Availability

• Prevent message loss for inbound emails to recipient’s mailbox

• Prevent message loss for outbound emails from sender’s mailbox to external SMTP perimeter

• Protect against server failure causing lost messages

• Switch to lagged copy of database

History of Transport High Availability

• Exchange 2007 - Transport Dumpster feature introduced

• Exchange 2010 - Shadow Redundancy feature introduced

• Exchange 2013 – upgrade to Shadow Redundancy

• Exchange 2013 – Safety Net (formerly Transport Dumpster)

• Exchange 2013 SP1 – Reintroduced Edge Role/Server

Exchange 2013 Transport High Availability Improvements

• Shadow redundancy makes copy BEFORE message is accepted or acknowledged

• Sending server does not need to be “shadow redundant aware”

• Shadow Redundancy is DAG and AD Site aware for boundaries

• Recall [not Outlook related] / Resubmit Capabilities EVEN for successful emails

Shadow Redundancy Requirements

• 2+ Exchange 2013 Mailbox Servers

• Single or Multi-Role Servers Supported

• Non-DAG Mailbox Servers must be in same AD site

• If a member is in DAG, other member must be in same DAG

Shadow Redundancy Support for Any SMTP Server

One SMTP session illustrated1) Start of Message from External SMTP to Primary Server2) 2013 Transport HA SMTP Copy to Shadow Server3) Primary Server Confirmation4) Primary Server End Message Confirmation to External SMTP

Image: MS Exchange Guru

Image: Microsoft Technet

Shadow Redundancy Configuration Options• “ShadowRedundancyEnabled” turn-on/off (default value is enabled)

• “RejectMessageOnShadowFailure” enforces that shadow copy is successful (default value disabled)

• “ShadowMessagePreference” provides option to copy to remote site vs local shadow copy (default value is PreferRemote). Remote site option only works for DAG members.

• “MaxRetriesForRemoteSiteShadow” for DAG members across 2+ sites (default value is 4). Failure results in local.

• “MaxRetriesForLocalSiteShadow” for retrying msg copy. (default value is 2)

• “ConnectionInactivityTimeout” time allowed for idle smtp session (default is 5 min on Send & 10 min on Receive). Questionable Technet note on Edge (1 min)

• “ConnectionTimeout” time allowed for active smtp session (default is 5 min)

Shadow Redundancy Work Flow

Reference: Microsoft TechNet Image

1) Inbound Email outside of HA boundary2) Duplicating Email to 2nd Server within boundary3a) Transport service to mailbox transport service3b) Mailbox transport service delivers to local mailbox database3c) Mailbox01 queues discard status for Mailbox03 for successful process. Mailbox01 moves copy into local Primary Safety Net.4) Mailbox03 polls Mailbox01 for discard status of primary message5) Mailbox03 determines Mailbox01 successfully processed, Mailbox03 moves the shadow message into the local Shadow Safety Net.

Safety Net Overview

• Formerly Transport Dumpster, renamed to help explain the functionality better.

• Safety Net stores messages that were successfully processed by Transport Service on mailbox server/DAG member

• [NEW] Safety Net is redundant (Primary & Shadow)

• [NEW] Supports DAG and non-DAG mailbox servers

• Transport Dumpster and Safety Net not fully compatible (2013 -> 2010, but not 2010 -> 2013)

• Once messages exits Exchange transport boundary, Safety Net’s job is done

Safety Net Scenarios

• If messages are lost, the message resubmissions are initiated by Active Manager (same AM functionality – run via Exchange Repilication service)

• Fully Automated & No Manual Intervention Needed

Primary Safety Net Originated1) After failover (auto/manual) of a mailbox database in a DAG

2) Offline for a period of time or after you activate a lagged copy of a mailbox database

When Shadow Safety Net is Called1) If Primary Safety Net fails to respond during message resubmission

for 12 hours, Active Manager will issue broadcast to Shadow(s).

2) Activation of Shadow(s) could result in duplicate messages for internal and most likely external for period of request (DSNs & NDRs suppressed). DSN = Delivery Status Notifications

NDR = Non-Delivery Reports

Safety Net Configuration Options* (*partial list)

• “SafetyNetHoldTime” is for length of time successful messages are stored Safety Net (default value 2 days)

• “ReplayLagTime” is amount of time Replication Service waits before replaying log files to passive database copy (default value not set). 0< is a lagged copy functionality.

Tip: if you make this 2< increase SafetyNetHoldTime (14 day max)

• “MessageExpirationTimeout” is how long ANY message are stored (default value 2 days)

• “ShadowRedundancyEnabled” is turn-on/off for all transport servers (default is on)

Requirement: Safety Net requires Shadow Redundancy

Config FYI: some config is UI

possible while others are CLI only

References Details

Overview of Transport High Availabilityhttp://technet.microsoft.com/en-us/library/jj657506%28v=exchg.150%29.aspx

Safety Net Microsoft Overviewhttp://technet.microsoft.com/en-us/library/jj657495%28v=exchg.150%29.aspx

Safety Net Microsoft TechNet Configuration Optionshttp://technet.microsoft.com/en-us/library/jj657495%28v=exchg.150%29.aspx

Shadow Redundancy from Microsoft TechNethttp://technet.microsoft.com/en-us/library/dd351027%28v=exchg.150%29.aspx

Thank you for attending tonight’s NY Exchange User Group Meeting.

Now for Question of the Month……

TechHit.com (Outlook add-ons) – raffling off any one of their products (SimplyFile [intelligent filing], EZ-Detach [easily detach multi-emails of attachments], MessageSave [backup, archive, save msgs], AutoRead

[mark as read/remove new mail icon], & QuickJump [quickly open/move between Windows folders].