Most of you out there have of course heard about Exchange 2007 and maybe even have seen some demo's. But I have a feeling very few of you have actually deployed it yet - not that you don't want to of course but these things take time. In this blog I'm going to give you the low-down on what's new in Exchange 2007 clustering and how it might apply in your current Exchange 2000/2003 environment (I'm not going to even mention Exchange 5.5 as I know you have all migrated by now!). This way when your users (or your boss), wants "more" e.g. better availability, better performance, "why can't I do X, Y or Z" etc., you'll have a bit of ammunition ... "well if you gave me some budget I think I could do something for you ...". You know, be the hero.
4 Cluster Flavours & 4 New Acronyms
Yippee - 4 new acronyms to confuse our colleagues and bosses and make us look smart. They are:
Let's have a closer look at them.
1. SCC - Single Copy Clusters - "Classic Clustering"
The original of the species is still with us but now known as Single Copy Clustering. This is where we provide redundancy for our servers but still have a single points of failure - the shared disks which host the cluster quorum and the Exchange databases and logs. In Exchange 2007, the fundamentals of how this works has not changed but Exchange 2007 introduces a number of optimisations designed to improve on what came before. The big changes are:
2. Continuous Replication - LCR, CCR, SCR
In the world of e-mail the replication paradigm had delivered significant benefits - think of cached-mode Outlook. Replication is GOOD - we like it. Continuous Replication (CR), AKA log shipping, is a proven concept in the enterprise database world. So how does it work in Exchange? Here's how:
LCR, CCR and SCR are different variations on this theme with different pros and cons. With LCR the replication process takes place on the same server. In CCR you use a different flavour of Windows Clustering called Majority Node Set to have a 2-node cluster. SCR can be combined with SCC, LCR and CCR to give you a whole raft of interesting options. The devil, as usual, is in the detail but once mastered will put you in the driving seat when it comes to delivering higher service levels to your end-users.
There's obviously a bit more to it than that (and if you want to know more have a look here - High Availability). There's also lots of good stuff on the Exchange Team Blog - for example have a look at this Video series - Exchange 2007 Cluster Continuous Replication (CCR).
To wrap up I just want emphasize that no matter how good the technology some things never change. Technology alone will never deliver the goods. The delivery of a high quality e-mail service depends on the combination of people, process and technology. So expect to put some work and budget into training for your messaging engineering and operations teams, the creation of lots of new and updated documentation and plenty of testing - both in the lab and in the production environment.
Be the hero.
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