Last post Jun 28, 2008 10:53 AM by kiphup
Jun 26, 2008 06:25 PM|BladesAway|LINK
I have been reading the deployment guides for HMC 4.5 and I'm a bit confused by a reference diagram that shows 3 servers for the CCR cluster. I thought that CCR was always a pair of servers. Can someone explain that to me. You can find the reference
model I am referring to in the 4.5 CHM file at Hosted Services->Hosted Exchange Server->.....Scalable Hosted Exchange Architecture.
I can see how 3 servers would be used in a SCC, with two actives and one passive, but CCR with 3 makes no sense to me.
Also, what is the most popular method of clustering among this group.... is it CCR or SCC? I see SCC as more cost-effective but nothing I see in the doc suggest that. What am I missing?
Jun 26, 2008 08:49 PM|DmitriG|LINK
One active server, one passive, one file share witness.
Jun 26, 2008 09:20 PM|BladesAway|LINK
Well that makes perfect sense now. How about the other part of the question? Got any advice there? I'm finding that if I spec out a 3 node SCC capable of supporting 6000 2GB mailboxes, that it is much more cost-effective than a 2 node CCR cluster supporting
the same mailbox configuration.
Thanks for the previous answer.
Jun 26, 2008 09:25 PM|PowerK6|LINK
Yes, the file share for this file share witness can be located on any type of Windows Server in your environment, but best practice is to use an Exchange 2007 Hub Transport Server in the Active Directory server site containing the nodes in the respective
The file share witness feature is an improvement to the current Majority Node Set (MNS) quorum model. This feature lets you use a file share that is external to the cluster as an additional "vote" to determine the status of the cluster in
a two-node MNS quorum cluster deployment.
Ref article: http://support.microsoft.com/kb/921181
Jun 26, 2008 09:35 PM|PowerK6|LINK
Solution Components -> Hosted Services -> Hosted Exchange Server 2007 -> Get Start with Hosted Exchange -> High Availability and Clustering Technologies -> Standby Cluster Replication vs. Cluster Continuous Replication
SCC and CCR are both options and both are supported for providing a reliable service. If you already have Storage Area Network (SAN) capacity or knowledge, you can use that with SCC. Otherwise CCR would provide the additional benefit of data availability and
the ability to make backup off the passive copy.
Jun 27, 2008 09:36 AM|DmitriG|LINK
... it is much more cost-effective than a 2 node CCR cluster supporting the same mailbox configuration.
Well... "Swiss knife" solution doesn't exist. Do whatever you think is better for you.
Jun 27, 2008 09:42 PM|filippg|LINK
Also, what is the most popular method of clustering among this group.... is it CCR or SCC?
SCC is the more often used method. Why? Beacause it's the "classic" Method, while CCR is newly introduced on Ex 2k7.
I'm not shure whether you got the fundamental difference: CCR is a cheap method for storage replication. You can use two Servers with built-in storage and have a redundancy of your data with it. Of course, the replication consumes some ressources on the
SCC doesn't replicate storage. Now, you've got two options. 1) just have one copy of your data. If your Disk-Array dies, your Service is down 2) Use replication on SAN-level. Every Storage-manufacturer offers a solution for Bit-wise-Mirroring. But these
solutions are very expensive in most cases (as the SAN allready is) and not allways easy to manage.
If you allready have a SAN infrastructure with replication and you've got the know-how: keep on using SCC (my suggestion). If you don't you should consider CCR.
Jun 28, 2008 10:53 AM|kiphup|LINK