Hi All,I'd like to implement Exchange server for my Company, they are located in differenct city and both of them will be connected as of this diagram below.http://img162.imageshack.us/my.php?image=itreeemailservicejpgfi3.jpgmy question is.... if the main Exchange server in Wollongong city is down, how can I still preserve the availability for Sydney user then ?I'd like to hear your idea and suggestion in this matter.Kind regards,Albert Widjaja T.

Dear Albert,You have two options :Option 1 : ClusteringYou can use CCR as a high availability for your exchange mailbox servers. Two servers will have a local database for all the users in wollongong and sydney. When one goes down , the other takes its place.Requirement :Clustered mailboxes cannot host any other exchange server role so total you needthe following servers for ourcomplete organization. Two servers with identical storage for Mailbox Cluster.One server can be used as a HUB and CAS ( havnt considered high availbility for these roles yet)One server as and Edge Transport Server.Advantages :High Availability for All maibox users.Disadvantage:If Wollogong site goes down or wollongong link from the internet is down then users in sydney will not be able to access their mailboxes.Option 2 : Seperate server in Sydney BranchYou can install a second server in the Sydney site , totally independant from the wollongong site.Requirement :You will need the following servers for your complete organization : For Wollongong SIte : One server for Wollongong Site as a HUB CAS and MAilbox. One server for Wollongong Site as a Edge Transpport Server For Sydney Site : One server for Sydney Site as HUB CAS and Mailbox.Advantages:Sydney Site will be totally uneffected with the server failure at the wollongong site.If the Wollongong site is down , Internal emails for sydney site will work fine.external Emails can be configured to run through the Sydney site as it is directly connected to the internet. Internet Emails can also be configured to land on the Sydney site by MX record updation.Diaadvantages :No high availabilty for Local server has been kept under mind in this design.further detail sharing can help re-organize the design appropriatly.RegardsAli

If the main Exchange server in Wollongong city is down, how can I still preserve the availability for Sydney user then? And what about Wollongong users in that event? Seems like Wollongong and Sydney are not too far away from each other. My suggestion would be: Concentrate all your effort on ensuring high availability in Wollongong, have all your users in Sydney connect to the Exchange servers in Wollongong.HA in Wollongong could be: 2 x DC/GC, mailbox CCR (2 servers), 2 x Hub/CAS, 2 x ISA 2006 and 2 x Edge. This design would handle several thousand users. You can have many variations over this theme, depending on the size of your organization, HA needs and money. A poor man's cluster would be one mailbox server with LCR. 1 x ISA 2006 and 1 x Edge could suffice with proper disaster recovery routines.For site resiliency you could implement a SCR box and a combined Hub/CAS server inSydney. Jon-Alfred Smith MCTS: Messaging | MCSE: S+M