At least 4 servers in one DAG?


  • Hi all,

    after reading , will the DAG need at least 4 members(or even numbers)?

    We have two site which are production and DR sites.
    I was planning to put two DAG members at the production site and one DAG member at DR site.  Will this spport?
    or Do I have to put 4 DAG members in one DAG?

    What's the best practice?
    Wednesday, February 17, 2010 8:18 PM

All replies

  • Hi John,

     Will the DAG need at least 4 members(or even numbers) ? No.
     DAG requires minimum one Exchange Member Server. It supports 16 memebers at the max.
     2 Member Server in Production Site + 1 in DR Site = 3 Member servers DAG is Supported.
     Its not mandatory to place 4 DAG members in the DAG.

     All the Best :)
    Sathish Kumar Elango | MCSE 2003 & MCSA Messaging |
    Wednesday, February 17, 2010 8:56 PM
  • While 4 nodes are not required you may see it suggested for a couple reasons.

    1. Folks who want to go with JBOD for storage. If you do not have at least 2 copies of each DB in a datacenter (and at least 3+ copies of each DB total across all datacenters) then Microsoft recommends sticking with RAID in that datacenter.

    2. To enable you to perform intra-datacenter switchovers/failovers without affecting any of the ancilliary functions like CAS/HUB/etc...
    Brian Day, Overall Exchange & AD Geek
    MCSA 2000/2003, CCNA
    MCTS: Microsoft Enterprise Server 2010, Configuration
    MCITP: Enterprise Messaging Administrator 2010
    Wednesday, February 17, 2010 11:10 PM