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DAC and Dialtone Recovery

what is DAC and Dial tone Recovery in exchange.
1 Solution
Simon Butler (Sembee)ConsultantCommented:
Is Google broken this afternoon?

DAC - datacentre activation coordination mode. Outlined on TechNet here:
Basically a way of ensuring that data centres come up in a controlled manner.

Dialtone recovery is a way of getting limited service back for end users, while a full data restoration is carried out. Also explained on TechNet.

It would have been quicker to just Google the terms than post a question.

AmitIT ArchitectCommented:
Let me explain you in lay man language.

What is DAC?
You enable this to avoid split brain at database level, when you switch back. Basically, Exchange will not allow Primary and Secondary Database to become active/active, when there is an issue, where primary datacenter unable to contact secondary and both should not try to become active. As this will make the database inconsistent. how it happens, there is 1 and 0 bit value.

What is Dialtone?
Where you use it, say you have a scenario, where you Exchange server goes down and you don't time to restore everything. Normally you use it, when you DB size is huge and take lot of time to restore, however you want to bring user back to production and restore data later, in those case you create dialtone db and bring your user back to production without any data. Later you merge the data by restore to recover db and then merge it back.

hope this helps.
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