1)What back up solution you recommend? 2)How you will implement High availability? (replication, DAG (2 servers)) Database Availability Group (DAG) Now that Exchange 2010 has been officially released and I am allowed to blog on the topic I wanted to start with what I believe is one of the best features added to Exchange 2010. There may be some heart break of the removal of a few features from Exchange 2007 however Database Availability Groups (DAG) is a feature that has been ask for over years. To better under what a DAG is let’s recap through Ex change. Exchange 2007 introduced LCR, CCR, SCC and SCR LCR (local continuous replication) this was mainly used for small business who wanted to replicate a copy of their Exchange database to another disk on the same server. SCC (Single copy cluster) was what I would call a traditional Exchange cluster which used shared storage to host the Exchange database.
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2) How you will implement High availability? (replication, DAG (2 servers))
Database Availability Group (DAG)
Now that Exchange 2010 has been officially released and I am allowed to blog on the topic I
wanted to start with what I believe is one of the best features added to Exchange 2010. There
may be some heart break of the removal of a few features from Exchange 2007 howeverDatabase Availability Groups (DAG) is a feature that has been ask for over years. To better
under what a DAG is let’s recap through Exchange.
Exchange 2007 introduced LCR, CCR, SCC and SCR
LCR (local continuous replication) this was mainly used for small business who wanted to
replicate a copy of their Exchange database to another disk on the same server.
SCC (Single copy cluster) was what I would call a traditional Exchange cluster which used
CCR (cluster continuous replication) was used to replicate Exchange database informationbetween 2 Exchange server allowing for hardware and storage redundancy but was limited to 1
Active node and 1 Passive node.
Basic deployment of CCR
SCR (standby continuous replication) was introduced in Exchange 2007 SP1 to provide theability to replicate Exchange databases to an disaster recovery location.
The concept of a DAG and how it functions I believe is easier learned by someone who hasn’tworked with Exchange clusters previously.
In Ex 200X an Exchange server was installed as either an Active or Passive cluster node at the
time setup.exe was run.
Depending on which version of Exchange you installed you had to create an Exchange virtual
server (EVS) which was changed to cluster mailbox server (CMS) in Exchange 2007.
When a user connected Outlook the mailbox server name was a clustered resource which movedbetween any number of nodes on the Exchange cluster. This allowed for no end user
configuration changes all the resource moved between physical servers
An Exchange database was associated with the clustered resource and when you open
EMC/ESM the only Exchange server name that was shown was the clustered node, let’s call is
CMS1. That means database one would always belong to CMS1 even when this moved betweenphysical machines.
Here comes the DAG
So now it’s time to forget everything that I just mentioned previously in this article aboutExchange clustering.
2. Right click and select New Database Availablity Group
3. We are now ask to fill in 3 pieces of information for our DAG
a. DAG name
b. FileShare witness (fsw) UNC path (can be any machine)
c. phycial location on the server that will host the fsw
You can see I am using my DC in the lab for the fsw machine, note that whatever machine youare using as the fsw needs to have the Exchange Trusted Subsystem group in the local Admins
6. We can now see that E14-ex1 was added to the DAG
If we open our Admin tools we will see the Windows clustering is installed and that E14-ex1 is a
member of the cluster
note: by default the DAG is set to use DHCP to assign and address to it, in the current build thereis no way to assign an IP to the DAG in gui. This can be done when adding a node to the DAG
from EMS.
Let see what it looks like to add the server from EMS
1. Open EMS (use the local shell currently) add-databaseavailabilitygroupserver GenieDag -mailboxserver E14-ex1 -databaseavailabilitygroupIpAddress 192.168.1.60