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Tag Archives: Exchange 2010

OWA Outlook Web Access – 500 error, Forms-Based authentication fails to start

In the process of creating a DAG lab i noticed that once the servers were in a DAG cluster, I was not able to log onto OWA, the symptoms were:

  • User could authenticate, if they failed to enter their creds they were asked to try again
  • Once they had successfully authenticated a 500 error was dished out by IIS.

A little digging found that Microsoft Exchange Forms-Based authentication fails to start, a manual start sorted this out in the short term, however for a longer term fix I changed the service behaviour to Automatic (Delayed Start), it now starts of its own accord.

I experienced these symptoms with Exchange 2010, SP2 RU4.

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HA Exchange 2010 two All-In-One servers in a DAG, CAS arrays, Windows NLB….. – confusion and solution

In the process of lab testing for the viability of a HA mail installation with HP’s E5000 series of messaging appliances I came up against some confusion about the configuration of the CAS array when using a 2 member DAG where the servers also host the CAS and HT roles. I am aware a hardware Load Balancer is required for this to work but was not clear on exactly how to configure exchange to work with such a device.

Initially in a lab I configured a DAG between two exchange 2010 VM’s, this seemed to be working as expected. Next instruction was to add both servers to a CAS array, and assign a VIP and put this in DNS.

I then configured a CAS array, assigned a VIP and configured the DNS record. The array included the two all-in-one servers, it created successfully  but none of my clients were able to connect, neither was i able to ping the array address. Further reading, in particular this: http://blogs.technet.com/b/exchange/archive/2012/03/23/demystifying-the-cas-array-object-part-1.aspx  led me to realise:

  1. Windows NLB is needed for a CAS array to work without additional hardware.
  2. Windows NLB is incompatible with Server 2008 R2 failover clustering.
  3. Server 2008 R2 failover clustering is needed for DAG…
  4. I need a DAG….
  5. Therefore i cannot use windows NLB…..

Which led me to read the “Best practices for networking and load balancing with the E5000 messaging systems” pdf on the HP site.

Essentially I’d gone about it backwards:

  • You still create the CAS Array, but use a VIP that is assigned to the load balancers and it is that IP that must be defined when you create the array. Once this is in place and the HLB is configured they proxy the requests to the separate CAS servers and all is good.
  • It seems the CAS array is  a simple object, a pointer more than a mechanism, a CAS array object does not load balance your traffic, Windows NLB does that or in our case, our hardware load balancer, all the object does is tell the mail client where to go to get mail.

Save yourself 15 minutes installing pre-req’s on an Exchange 2010 install on Server 2008 R2

Copy and paste the script on the page linked here to a notepad file, save as a .ps1 and run before installing exchange.

Even downloads the filter pack for you http://www.bhargavs.com/index.php/2009/11/18/script-to-install-exchange-2010-pre-requisites-for-windows-server-2008-r2/

Many thanks to the author of the linked page Bhargav Shukla, the original author of the script Anderson Patricio and Pat Richard. With lab installs i think this has given me around 2 hours of my life back all told.