With DAGs, if you have an odd number of DAG nodes in the same DAG (Cluster), you have an odd number of votes so you don’t have a witness. This means that 50% of your votes (server votes and/or 1 file share witness) need to be up and running.
This is one of the nice things I like about Exchange 2010 High Availability, is that if your DAGs go down, you can allow the copy in the DR Site to automatically activate (provided the Database Activation Policy as described above allows it to automatically mount) whereas in Exchange 2007, you had to manually activate any SCR copy.Įxchange 2007 and Exchange 2010 Clusters both use Majority Node Set Clustering. In this case, the RPC Client Access Array in the Primary Site will still successfully be able to provide mailbox access to the databases mounted on SecondarySiteMBX0102 in the DR Site. Should PrimarySiteMBX01 and PrimarySiteMBX02 go down (as illustrated below), SecondarySiteMBX0102 can automatically mount the database because majority is still there for quorum. You can see there are 6 nodes and 3 copies of each database. To make it a bit more clear, the following image shows database distribution. PrimarySiteMBX01 and PrimarySiteMBX02 are mirrored with SecondarySitMBX0102 in the DR Site and PrimarySiteMBX03 and PrimarySiteMBX04 are mirrored with SecondarySiteMBX0304 in the DR Site. PrimarySiteMBX03 and PrimarySiteMBX04 in the Primary Site are mirrored in terms of database copies.
So PrimarySiteMBX01 and PrimarySiteMBX02 in the Primary Site are mirrored in terms of mailbox database copies. Let’s say, we currently have a lack of funds for storage which prohibit the ability to have mailbox database copies on all servers. Let’s say we have 6 DAG Servers with 4 in the Primary Site and 2 in the DR Site with no modifications to the Automatic Activation Policy (DAG Servers in the DR Site can automatically mount databases). Set-MailboxServer -Identity MailboxServer -DatabaseCopyAutoActivationPolicy Unrestricted Example You can use the following command to prevent the database from being considered in the Automatic Activation Process: Let’s say you wanted to disable a specific database from being considered in the Automatic Activation Process. There is something called Database Activation Policy. Automatic ActivationĪs I just eluded to above, it is possible to turn off automatic activation on databases and servers.
In this scenario, the RPC Client Access (and array) can access the mailbox databases that are mounted in the DR Site. In the case where all database copies go down in the Primary Site, your databases can automatically failover to the DR Site as long as you allow automatic activation on the DR Servers (yes, you can turn off automatic activation on databases and servers) and as long as you still have Majority for your Quorum. Scenario #2 – Server Failure(s) in Primary Site and Disabling Automatic Activation for Databases and Servers The client (after the DNS record flushes – recommended for TTL value to be 5 minutes for DNS records in site resilient solutions) will then start to connect to the DRSiteCAS which will then access the database in the DR Site. You change to point to DRSiteCAS instead of PrimarySiteCAS. One out of several DNS records you change will include the CAS Array.
#MICROSOFT EXCHANGE RPC CLIENT ACCESS NOT STARTING SBS 2011 REMOTE UPDATE#
As a part of the manual site switchover process, you must update the DNS records in your Primary Site to point to the CAS infrastructure at your DR Site. Let’s say you have a Client Access Server Array called. A common question I see out there is if the RPC Client Access Service (including Client Access Service Arrays) can access databases in other sites.
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