Definitions for MountDialOverride and auto mount dial settings?
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Wednesday, October 28, 2009 6:19 PMI began working through these on my own and thought I would ask here.. The TN article:
http://technet.microsoft.com/en-us/library/dd298068(EXCHG.140).aspx
It says the default is lossless. So when I pick the GUI of None, is it doing the same as lossless? What exactly are these choices and what are the impact and actions taken when each is selected? Just trying to get a better definition. I read the examples in the linked article above, and they make it clear that it changes the way the target activation server mounts the database, but not in what fashion.
Anyone?
All Replies
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Wednesday, October 28, 2009 7:33 PM
So when I pick the GUI of None, is it doing the same as lossless?
Think about what you're executing, a MountDialOverride.
In this case None = Do not override the current Mount Dial setting during this switchover.
Brian Day / MCSA / CCNA, Exchange/AD geek. -
Wednesday, October 28, 2009 8:30 PMI guess the next question - please define mount dial better. I couldn't find in any documentation yet.
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Wednesday, October 28, 2009 8:58 PM
I'm not writing a blog article for you am I? ;) j/k hehe
Mount Dial is the same as it was in Exchange 2007 with a couple tweaks. It remains the parameter that determines if a passive copy of a DB copy can come online or not depending on how many (if any) log files were in the copy queue length when the active database copy went offline.
The setting is per server and you can see what your 2010 servers are set to by issuing Get-Mailboxserver | FL Name,AutoDatabaseMountDialBestAvailability is the default setting.
BestAvailabilityIf you specify this value, the database automatically mounts immediately after a failover if the copy queue length is less than or equal to 12. The copy queue length is the number of logs recognized by the passive copy that needs to be replicated. If the copy queue length is more than 12, the database doesn't automatically mount. When the copy queue length is less than or equal to 12, Exchange attempts to replicate the remaining logs to the passive copy and mounts the database.GoodAvailabilityIf you specify this value, the database automatically mounts immediately after a failover if the copy queue length is less than or equal to six. The copy queue length is the number of logs recognized by the passive copy that needs to be replicated. If the copy queue length is more than six, the database doesn't automatically mount. When the copy queue length is less than or equal to six, Exchange attempts to replicate the remaining logs to the passive copy and mounts the database.LosslessIf you specify this value, the database doesn't automatically mount until all logs that were generated on the active copy have been copied to the passive copy.
The first two will initiate the transport dumpster feature to kick in if there were any missing logs when the database copy wsa brought online.
Brian Day / MCSA / CCNA, Exchange/AD geek. -
Wednesday, October 28, 2009 10:20 PMOnly partially helping it along. I was writing on 2010 DAG and felt that I couldnt find good definitions.. I give credit where it's due! Have a blog you want me to link when I reference you?
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Wednesday, October 28, 2009 10:23 PMI have to admit - all of those sound like they do the same thing. Attempt to copy logs, then mount.
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Wednesday, October 28, 2009 10:50 PMPretty much. It just depends on how many logs are accepted to be completely lost and *still* mount the DB. You'll notice "Best Effort" isn't listed above for definitions, but shows up in places like EMC. A couple oddities on that one MS is currently looking into.
1. It is currently missing from the documentation.
2. I just found that it doesn't work with Set-MailboxServer -AutoDatabaseMountDial:BestEffort
3. It does seem to work with Move-ActiveMailboxDatabase -MountDialOverride:BestEffort
Brian Day / MCSA / CCNA, Exchange/AD geek. -
Wednesday, October 28, 2009 10:50 PMNot yet. <sniff> I want to start one up, but haven't really found the time.
Brian Day / MCSA / CCNA, Exchange/AD geek. -
Wednesday, October 28, 2009 11:05 PMUpdate from MS, "BestEffort" is any logs lost in E14. It also is not allowed as a permanent setting (that's why set-mailboxserver didn't work) and thus only available during a manual activation (why it works with move-activemailboxdatabase).
Brian Day / MCSA / CCNA, Exchange/AD geek. -
Tuesday, August 24, 2010 3:19 PM
Hey Brian,
Sorry to jump into you guys' thread here. It looks like the default in 2010 (for us) was "GoodAvailability" based on the command you provided (Get-Mailboxserver | FL Name,AutoDatabaseMountDial). I assume that this means in a failover scenario, the HA copy in the local site will not mount if there are more than 6 logs in the copy queue, correct?
Thanks, your explanations have been very helpful.
-Brent
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