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CAS Arrays inc DR Failover (Exchange 2010)

Please can someone confirm this basic design for CAS array setup + DAG & fail over in a DR scenario. I have read some conflicting articles and wanted to confirm my understanding

Site 1
Exchsvr1 - 3 roles
Exchsvr2 - 3 roles
80% of users here, the rest on remote sites

Site 2 (DR)
Exchsvr2 - 3 roles
DR facility

CAS Array
CAS Array 1 - casarray1.domain.local (5min TTL) - DNS RR to exchsvr1 & 2
CAS Array 2 - casarray2.domain.local - DNS A to exchsvr3

DR situation
Manually edit internal casarray1 DNS record to point to exchsvr3

DAG
One DAG (DAC enabled) File Witness on site1 member server, secondary File Witness on site 2 member server
A copy of all databases on all servers (50% of active on exchsvr1 & 50% of active on exchsvr2) preference to be set so standby db replica (site 1) is used before DR replica on site 2)

DR situation
Users will connect to and use mbx db on exchsvr3 (due to manual DNS change of CAS array)

ASKER CERTIFIED SOLUTION

Will Szymkowski

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Stuart

ASKER

Thanks for the link somehow i missed that question when searching on here :(

I didn't realise Outlook has the intelligence to redirect to a different CAS array, i thought the config was saved in the users .ost file.. and if you wanted to change the CAS array it would be a manual change or script.

Will Szymkowski

Its really not the intellegency of Outlook more the Autodiscover Service that it uses. As long as your clinets can reach the DR site, when Outlook is launched it will use Autodiscover which will find what server the Active Mailbox resides on. Then it uses the CASArray in that AD Site to connect to the mailbox.

Will.

Stuart

ASKER

Understood thanks!