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Windows Server Forum / Exchange Server / Design / February 200799.9 service availability
Hi All, Customer is looking to migrate from Notes to Exchange 2007 and one of the main goals is achieving 99.9 of email and collaboration service availability. They have 3 AD Sites belonging to an AD Forest/Domain, AD Sites are all well connected (close to LAN) they have around 1000 users/mailboxes per site. They want to minimise the number of servers used but keeping in mind high availability and contingency topics as a main goal I would like to know what your opinions are and getting your feedback because looks like Exchange 2007 is cool but to provide maximum availability you may need to deploy many servers. I am thinking in: 3 Mailbox Servers using LCR or SCC, 1 Server per site 2 Hubs (DNS round robin) and CAS Servers (NLB) per site (both roles in the 2 servers) 2 Edge Servers (NLB) This ends up with a total of 9 servers using LCR or 12 servers using SCC Question 1: do you see any space here for implementing CCR? I do believe they have to be configured in pairs so you would need 6 servers in a king of ring topology so .. Question 2: what about deploying just 1 Hub or CAS server per site and this goes down? Is there any way to move all the client requests and mail flow to other server in other site? I don't think so but want to double check thanks >Hi All, > [quoted text clipped - 31 lines] > >thanks You will only be able to run CCR if the networking team can implement a network trunk between the site with the live server and wherever you put the CCR replicas. Before I go any further, what storage are you planning? They are talking about using NetApp Snapmirror for Exchange thanks >>Hi All, >> [quoted text clipped - 43 lines] > > Before I go any further, what storage are you planning? >They are talking about using NetApp Snapmirror for Exchange > >thanks If you have SnapMirror then you can put away all thoughts of LCR and CCR as you just do not need it. Sit down with your storage admin or call the people who sold you the Filer and talk to them about Exchange 2007 configuration. They may not be up to speed on it it's the same as 2003 so they will be able to help you fully. Take a look at: http://www.netapp.com/library/tr/3407.pdf which will help you understand SnapMirror if you're not already familiar with the product. Mark, I don't know so much about SnapMirror but my as far as I know NetApp SnapMirror provides Data Availability copying the DB and logs to a secondary location using a cheap storage (if you want of course) what I don't see here is the service availability support. CCR enables you to use a passive node to support your users when the active node is down. Using the NetApp solution you should create a new storage group pointing to the replicated DB, this process is not immediate so the service can be down for a while What would you recommend here? thanks >>They are talking about using NetApp Snapmirror for Exchange >> [quoted text clipped - 10 lines] > help you understand SnapMirror if you're not already familiar with the > product. In the CCR model, you'd use log shipping to send the logs to the passive node where they are replayed. When a log file fills to 1M, it is shipped, validated, and replayed. That may be every few minutes or less on a very active SG, or a lot longer if the SG is not so active (yes, there is the dumpster on the hub, but there are issues as to placement as well). MS recommends VSS backups on the Seconday node due to the IO intensity of copy on write snapshots and the IO activity associated with validating the backup (per kb822896), so backups potentially lag as well. There's clearly a gap here depending on how busy the storage group is. If it's right for you really depends on what your SLA is. At a minimum, with Netapp you get space utilzation similar to RAID 5 with no write penalty. You also get to leverage the low IO impact of snapshots on the platform and prerform them on both the active and inactive nodes at least eliminating this part of the gap. In the designs Mark refers to, you would you the good old shared storage cluster and snapmirror replication to a DR site using standby clusters. Locally, The RTO is as long as it take the cluster to failover (a couple of minutes) and the RTO is up to the minute. In the event of site failure, the RPO can be as low as 5 minutes (it's dependent of the frequency of log snapmirror updates) or so and the RTO is a few hours (because you implement a standby cluster). The point with the RPO in this case is that it is expressed in terms of time - the way business objectives are expressed. This is very similar to designs for Exchange 2003 out there and proven in the real world today. It falls within the support policy for replication of Exchange data because snapshots, not live data, are what is replicated. http://www.netapp.com/go/techontap/matl/three-tradeoffs.html http://www.microsoft.com/technet/technetmag/issues/2006/10/FailoverClusters/defa ult.aspx John > Mark, I don't know so much about SnapMirror but my as far as I know NetApp > SnapMirror provides Data Availability copying the DB and logs to a [quoted text clipped - 23 lines] >> help you understand SnapMirror if you're not already familiar with the >> product. Thanks John, They have 1000 mailboxes in each Datacenter so, to achieve what you say below, I see ... they would need 2 servers in site 1 working in a SCC model replicating the data using snapmirror replication to other 2 nodes stand by cluster and other 2 servers in site 2 with the mailboxes from site 2 replicating the data to site A using snapmirror to other 2 nodes stand by cluster this ends up with 8 servers and 8 enterprise editions of Exchange + all the other server roles what seems to be too much for them, They want to minimise the number of servers used but keeping in mind high availability and contingency topics as a main goal, So I would see couple of chances here: Using CCR ( 4 servers) Site 1 - 1 Active Node with 1000 mailboxes from Site 1 and 1 passive node with the 1000 mailboxes from the Site 2 replicating the data between DC using snapmirror Site 2 - 1 Active Node with 1000 mailboxes from Site 2 and 1 passive node with the 1000 mailboxes from the Site 1 doing the same than above or Using 1 SCC (8 servers) in each location and replicate the data to the other datacenter using netapp solution what do you think? thanks Jesus > In the CCR model, you'd use log shipping to send the logs to the passive > node where they are replayed. When a log file fills to 1M, it is shipped, [quoted text clipped - 56 lines] >>> help you understand SnapMirror if you're not already familiar with the >>> product. In the SCC model, if the source is A/P, then the standby cluster can be a single node. This will save a couple of hosts. The CCR model would certainly be a lower cost solution and it may well work for them. You'll need to sit down and have an RPO/RTO discussion centered around their business requirements to find out. > Thanks John, They have 1000 mailboxes in each Datacenter so, to achieve > what you say below, I see ... [quoted text clipped - 90 lines] >>>> help you understand SnapMirror if you're not already familiar with the >>>> product. |
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