Hi We are running Exchange 2007 SP2 in a CCR setup using W2K8 server OS. Let's say I have two servers - exch1.domain.com and exch2.domain.com. The CMS name is exch.domain.com I then have an issue with one exch1.domain.com which is the "active" node for exch.domain.com Am I good to failover to exch2.domain.com? As long as users are using cached Outlook mode, they will not really notice a difference, am I correct? And there will definately be no mails lost?

With cached mode, they *probably* will not notice but it depends what they are doing. The databases are offline for a bit of time, so if the users try to click 'send/receive' at this time they might see an issue. It might also seem like mail takes another minute or so to come in or go out. If there are a lot of storage groups and a lot of log files to play, it can take a while to mount the databases on the new active node. It can also take a bit longer if the nodes are on different IP subnets, since DNS has to be updated and the TTL needs to expire on the client. Without cached mode, things are even more noticeable. As for whether you will lose mail - this depends on the health of the replication and your AutoMountDial setting. See http://technet.microsoft.com/en-ca/library/aa998584(EXCHG.80).aspx

Couldn't write it better :) Make the failover after business hours if that's possible? Is the replication health OK? Make sure you read through the link cn9 posted Jonas Andersson MCTS: Microsoft Exchange Server 2007/2010 | MCITP: EMA 2007/2010 | MCSE/MCSA Blog: http://www.testlabs.se/blog

Agree with cn9 Additional Info: “It takes just as long to fail over from Node1 to Node2 as it does to fail over from Node2 to Node1. Typically, this would be under two minutes. On larger servers, scheduled outages typically would be less than four minutes” ---------Refer to <Cluster Continuous Replication> “When a failover is experienced that is not lossless, the clustered mailbox server automatically requests every Hub Transport server in the Active Directory site to resubmit mail from the transport dumpster queue” ---------Refer to <New High Availability Features in Exchange 2007 SP1> Transport dumpster will minimize the data loss for end users. However, there still have situations that data loss can’t be prevented by transport dumpster: · Drafts folder for any Microsoft Outlook clients in online mode · Appointments, contact updates, property updates, tasks, and task updates · Outgoing mail that is in transit from the client to the Hub Transport server. There is a period of time during which the e-mail message only exists on the sender's Mailbox server.Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.