Exchange 2010 DAG

timgreen7077 used Ask the Experts™
I will be testing DAG HA in a production environment. We have a production site and a DR site. Replication across both sites are good. Its a 4 node dag with 2 mailbox servers in the prod site and 2 in the DR site. I will run the startdagmaintenance.ps1 script on server 1 which will active the passive copies locally to server 2 according to the DB preferences. But the question is can I also run the startdagmaintenance.ps1 on server 2 also so that the passive DBs will activate on server 3 and 4 in the DR site since both servers in production are in maintenance mode. Can both server 1 and 2 be put in maintenance mode.
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I don't use the DAG maintenance script. I perform it's functions manually.  I just read through the code though, looks like there is a default 2 copy minimum which your DAG look like it can satisfy.

My DAG's are configured just like yours 2 servers in one site 2 in another.  Basically I run updates on any 2 servers at a time, the trick is making sure you maintain quorum.  So if you have a 4 node DAG as long as the remaining 2 servers and the witness are up to make the majority (3) you're fine.  Just know thy risks, as an untimely WAN issue could really cause you some problems depending on the servers you're doing maintenance on.
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If you are taking two servers down you are going to need an FSW. You cannot operate a DAG with two nodes active without one.


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