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Windows Server Forum / Exchange Server / Design / January 2007Question on CCR design for geographically dispersed datacenters
Hello, I've reading up on CCR with hopes of being able to use it as the crux of a site disaster recovery solution for some of my clients. At first glance I was very excited to read about this new feature, but now the more I read the more I'm preplexed at how such a thing is supposed to work with nodes spread over multiple sites. Quotes from: http://www.microsoft.com/technet/prodtechnol/exchange/e2k7help "CCR is designed to be either a one or two datacenter solution, providing both high availability and site resilience." and "Mailbox servers in a geographically-dispersed cluster require that a single Active Directory site be stretched between the data centers because all nodes in the cluster must be on the same subnet." Maybe I'm missing something, but how can you have nodes in different sites be on the same subnet? Any WAN link I've ever worked with requires that each site have it's own unique subnet. If anyone has some insight to this paradox, I'd greatly appreciate it. thanks You need to speak to your network guys about setting up VLANs /Simon > Hello, > [quoted text clipped - 22 lines] > > thanks Correct, you will need a VLAN. You will also need some very significant bandwidth. I can't find it documented, but HP experts presenting at Exchange Connections in Las Vegas recommended 100Mbps minimum. You probably want to check out this article, which reviews some of the third party products you can use to accomplish your goal. http://www.infoworld.com/article/06/10/02/40TCfailover_3.html The company I represent, SteelEye Technology, is in this report. I can say that we can support the environment you describe. Please feel free to contact me directly if you need additional information. David. A. Bermingham, MCSE, MCSA Senior Systems Engineer www.steeleye.com > You need to speak to your network guys about setting up VLANs > [quoted text clipped - 26 lines] > > > thanks- Hide quoted text -- Show quoted text - The article describes 3rd party "CCR" solutions for 2003. His questions were regarding 2007 (or more specifically Windows 2003 cluster single subnet limitations) It would be interesting to hear what you (SteelEye) and the other vendors doing in regards to 2007 & CCR. In Scandinavia, where I am based, 100Mbit is not considered "significant bandwidth". Most companies in the market for CCR have considerably higher bandwidths and more often than not some sort of QoS in place. Microsoft also support the soution he describes ;o) /Simon > Correct, you will need a VLAN. You will also need some very > significant bandwidth. I can't find it documented, but HP experts [quoted text clipped - 45 lines] >> >> > thanks- Hide quoted text -- Show quoted text - The three areas that I anticipate 3rd party solutions will address include the following... -Support for spanning different subnets (which MS plans to support with Longhorn I hear) -Support for low bandwidth links (T1, T3, etc.) -Support for Physical-to-Virtual clusters -Support for running the Hub, Client Access and Mailbox roles all on the same box (MS supports only the Mailbox role on a CCR node I would say most of the 3rd party solutions will address at least these current limitations with CCR David A. Bermingham, MCSE, MCSA:Messaging Senior Systems Engineer www.steeleye.com > The article describes 3rd party "CCR" solutions for 2003. His questions were > regarding 2007 (or more specifically Windows 2003 cluster single subnet [quoted text clipped - 56 lines] > > >> > thanks- Hide quoted text -- Show quoted text -- Hide quoted text -- Show quoted text - >The three areas that I anticipate 3rd party solutions will address >include the following... > >-Support for spanning different subnets (which MS plans to support >with Longhorn I hear) So they have said. I wouldn't actually place any store in that and will (do) suggest that the network teams set up a Trunk between the networks. It's not just Exchange that you have to consider when doing a site failover (which is what you are allowing for when cross-siting CCR) so sorting out the issue of client access to your data centre resources in a seamless manner is a network problem primarily. Too many people try and come up with all singing, all dancing solutions for Exchange and forget about such trivialities as Domain Controllers. >-Support for low bandwidth links (T1, T3, etc.) >-Support for Physical-to-Virtual clusters There is a quoted comment from the Head Cheese in the Exchange PG about Virtualisation. Some of the reasoning behind the 64bit only and the lack of 64 bit guests boils down to their lack of enthusiasm for it. I think it'll be huge and people will be falling over themselves to put VMware and P2V solutions. I doubt Microsoft will be too bothered about it because they don't have a decent (and in the case of 2007 even a viable) platform to do the V part of P2V. >-Support for running the Hub, Client Access and Mailbox roles all on >the same box (MS supports only the Mailbox role on a CCR node I don't see that as anything that would be worthwhile. If I put the HT on the MB role and then lose the MB, I lose a chunk of messages that would otherwise be replayed from the dedicated (or with CAS) HT box (or vmware image) sitting elsewhere. >I would say most of the 3rd party solutions will address at least >these current limitations with CCR To an extent but some of the perceived limitations with CCR are actually solved by either using a SAN properly (boot from SAN and simply flip the images - job done (at the 30,000 feet level)). The limitations are indeed many and the bringing into the fold of current geographical clustering technologies would be most welcome. >David A. Bermingham, MCSE, MCSA:Messaging >Senior Systems Engineer [quoted text clipped - 60 lines] >> >> >> > thanks- Hide quoted text -- Show quoted text -- Hide quoted text -- Show quoted text - > > Hello, > [quoted text clipped - 22 lines] > > You need to speak to your network guys about setting up VLANs thanks for your reply, I have no trouble setting up a VLAN (have set up hundreds over the years), but I just don't see how this fits. How do you propose getting a VLAN to span across multiple sites? My typical site to site connection would be using a VPN or point-to-point circuit. All of this necessitates distinct IP subnets in each site with the router or firewall routing traffic in between them. The only thing I can think of is somehow bridging the two sites so the joint network is in effect flat. But, this just doesn't seem feasible to me, with all the broadcast traffic which would then traverse the WAN link. Seems like a waste of bandwidth. I had envisioned CCR as a viable replacement for other asynchronous replication products such as XOSoft WanSync, Doubletake or EMC's RepliStore. Perhaps I'm just misguided with that assumption? You want to explore the following article to bridge your two sites... http://www.cisco.com/en/US/tech/tk389/tk689/ technologies_tech_note09186a0080094663.shtml#vlanrouting On Jan 25, 4:27 pm, goo...@dhnet.dhs.org wrote: > > > Hello, > [quoted text clipped - 36 lines] > replication products such as XOSoft WanSync, Doubletake or EMC's > RepliStore. Perhaps I'm just misguided with that assumption?- Hide quoted text -- Show quoted text - |
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