Exchange 2010 Sp3 Timings

It depends on several factor, hardware, Exchange current service pack level etc. However, as per my exp with proper planning it should not take more than 2 hours per server. Including reboots etc. However, I suggest you to upgrade to RU1 also along with SP3. Use my article for installing it with least downtime and proper planning

http://www.experts-exchange.com/Software/Server_Software/Email_Servers/Exchange/A_10389-Steps-for-Upgrading-Exchange-2010-SP1-to-SP2-with-RU3.html

Though it is for SP1/Sp2, however steps are similar, i wrote similar for Sp3. Pasting below:
Steps Upgrading Exchange 2010 SP1 or SP2 to SP3:


My Lab Setup: 2 node Multi-role server with DAG.

1) Upgrade the schema for Exchange 2010 SP3. If you have Enterprise and Schema Admin rights, setup will do it automatically, however if not, then AD team is required to perform this task.

Purpose of this Schema Update:
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In Order to have the Exchange 2010 SP3 deployed across the environment, it is a prerequisite to have the Active Directory Schema to be extended for supporting Exchange 2010 SP3. During this upgrade, the Active Directory Schema will be extended to support Exchange 2010 SP3.

Steps to be performed for this upgrade:
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Reference Article –
http://technet.microsoft.com/en-in/library/bb629560(v=exchg.141).aspx

Prerequisites: AD account need to be member of following groups
Member of: Domain Admin, Enterprise Admin, Schema Admin

Install Active Directory Management Tools (Run this Command, if Required)
ServerManagerCmd -i RSAT-ADDS

Software Location Exchange 2010 SP3
http://www.microsoft.com/en-us/download/details.aspx?id=36768

Download it and extracting it run below command for preparing the schema.

 setup /PrepareLegacyExchangePermissions (Optional):
 Check C:\ExchangeSetupLogs\ExchangeSetup.log for successful completion
 Setup /PrepareSchema
 Check C:\ExchangeSetupLogs\ExchangeSetup.log for successful completion
 Setup /PrepareAD /OrganizationName:"Your Org Name"
 Check C:\ExchangeSetupLogs\ExchangeSetup.log for successful completion

How to verify schema version?
http://technet.microsoft.com/en-in/library/bb125224%28v=exchg.141%29.aspx

2) Steps for Upgrading Exchange 2010 to SP3

Software Location:
1) Exchange 2010 SP3: http://www.microsoft.com/en-in/download/details.aspx?id=36768

Note: Any Interim Updates for Exchange Server 2010 must be uninstalled prior to installing this update.

As I have all roles in one server in a 2 node DAG. Kindly perform the below steps.

Phase 1: Upgrading Database Availability Groups to Exchange 2010 SP3 (Start with Passive)

Note: Make sure to take full Exchange backup, including system state or any custom setting related to CAS role. Do save the OWA folder under bin path too. During SP3 installation, Exchange setup removes all SP2 related folders; in case you have any proxying it might fail, so make sure to upgrade all servers, however one by one.

1) Open Exchange Management Shell, browse to script folder and run below command
     
.\StartDagServerMaintenance.ps1 -serverName servername

Note: This script move all Exchange related component including database to another server.
           
2) Disable the Forefront by using below command (It might ask you to stop few Exchange services)

fscutility /disable

3) Stop the OS Antivirus services and Monitoring Agent for Microsoft Exchange Server

4) Verify Backups are completed.

5) Run the SP3 setup files using GUI or goto run setup /m:upgrade. If you are getting IIS component error goto run setup /mode:upgrade /installwindowscomponents

Note: If you are getting this error "A Restart from a Previous Installation is Pending"

Open regedit and delete the HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\PendingFileRenameOperations key and Rerun Setup.

Ref: http://technet.microsoft.com/en-us/library/cc164360(v=exchg.80).aspx

6) Reboot the server

7) After reboot verify below logs for any error:
     
Event Logs
 
Setup Logs (C:\ExchangeSetupLogs)

Services - All Exchange related services are running.
     
Check IIS Settings are not changed.
     
Check Authentication settings from EMC for OWA/OMA/ESW. If you find any change revert back to old.
     
8) Enable Forefront Protection for Exchange. Command fscutility /enable (It might ask you to stop few Exchange services)

9) Start OS Antivirus and Exchange Monitoring Agent Services
     
10) .\StopDagServerMaintenance.ps1 -serverName servername

11) Now use same steps on another server in DAG.

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Phase 2: Upgrade Management Tools

If you have installed management tools in any other machine make sure to upgrade those also.
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Finally: - how to verify the upgrade.

Goto Powershell and type below command.

GCM exsetup |%{$_.Fileversioninfo}