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Explosive Growth

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  • Explosive Growth

    I just completed the deployment of a 1.5TB Exchange environment for a client. The client was on hosted Exchange and want to move in-house as the cost of 200 users was too much. This weekend we moved everything over to our new DAG group and everything seemed fine, until I looked at growth. The client’s database grew 100GB in a 24 hours period. Looking into this shocking number I found the cause.

    The company is dependent on distro lists (I know what you are thinking, it’s not that). The users wanted a method to identify what messages are for them and not a distro list so they created a server side processing rule in Outlook.

    “When a message comes to inbox with my name in the TO, Send a copy to the Inbox.”

    The Outlook client seemed to deal with this destructive rule, but the Exchange back-end didn't and grew and grew. When I compare a mailbox report to another one an hour old, it would show the users with these rules as growing 7 times faster than the company journal mailbox. I quickly removed these rules via OWA, but it seems that some users had a rule running on the client side also.

    I now have 200GB of messages that do not show up in their inbox, but the server seems to hold on to them in the database. My first assumption was that the automatic maintenance jobs would see this and purge the messages, but when I run a whitespace report I get minimal recovery of space. I change the deleted items retention to 0 days to see if that would acknowledge the white space, but it didn’t.

    I have a few questions I am hoping the community can help me out with:

    1. Why didn’t this issue expose itself on the hosted Exchange platform? I figure it is because they were clustered and were constantly running offline maintenance of some sort.

    2. How can I get this data off the database? I am thinking offline defrag, but not sure if it will work if the white space is reporting only 5GB of recoverable space.

    3. Is there something that I can do from the server end that would prevent a user from such growth? One user it 20 minutes increased 185 items and 111MB, while the journal for the whole company grew by 29MB and 133 items.

    I want to stop this behavior, prevent this behavior and recover the space.

    2x Exchange 2013 SP1 CAS servers on Server 2012R2
    2x Exchange 2013 SP1 Mbox Servers on Server 2012R2
    DAG replicating 5 databases between the two Mbox servers

  • #2
    Re: Explosive Growth

    You cannot offline defrag a DAG.
    You would have to break the DAG to do that.
    If you are going to break the DAG then you may as well create a new database on the other server, move all the mailboxes to that other server, drop the original, add it back in to the DAG. No downtime, no risk.

    I have never done an offline defrag on Exchange 2007 and higher, no point.

    Outlook has probably hidden the messages in conversation view or something like that.

    Simon Butler
    Exchange MVP

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