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SQL Server Forum / Other Technologies / Clustering / February 2006Active/Active/Active/Passive and Database Mirroring
We have 4 systems that was initially planned to be joined into an Active/Active/Active/Passive cluster with SQL 2005. Can anyone offer a suggestion on the number of instances to install per node? Does each instance need seperate Disks for the Database, Logs and TempDB? If we stay with this configuration will Database mirroring still be an option with the configuration once it is supported by MS. Instances are installed to the entire cluster, but can be set to prefer certain nodes. I personally like N-1 clusters (N nodes, N-1 Instances), just to simplfy management, but other that is not an absolute, inflexible standard. Each instance has completely separate resources; IP address, Data disks, Log Disks, TempDB, and Network Name. Each instance works and appears as a separate and distinct SQL Server.  SignatureGeoff N. Hiten Senior Database Administrator Microsoft SQL Server MVP > We have 4 systems that was initially planned to be joined into an > Active/Active/Active/Passive cluster with SQL 2005. [quoted text clipped - 4 lines] > If we stay with this configuration will Database mirroring still be an > option with the configuration once it is supported by MS. Thank you for such a fast response. In the active/active/active/passive configuration is it possible to load balance the 3 instances over 3 nodes? Ideally we would like to create 1 instance split over 3 nodes... is this possible (see EX1) or do we have to do something like EX2? Ex1: (1 instances - share over 3 nodes) Node A = Instance1 (load balanced) Node B = Instance1 (load balanced) Node C = Instance1 (load balanced) Node D = Passive Ex2: (4 nodes - 1 passive = 3 instances split over 3 nodes) Node A = Instance1 (load balanced) Node B = Instance2 (load balanced) Node C = Instance3 (load balanced) Node D = Passive > Instances are installed to the entire cluster, but can be set to prefer > certain nodes. I personally like N-1 clusters (N nodes, N-1 Instances), [quoted text clipped - 13 lines] > > If we stay with this configuration will Database mirroring still be an > > option with the configuration once it is supported by MS. SQL Clustering is a failover technology only. It does not load-balance. SignatureGeoff N. Hiten Senior Database Administrator Microsoft SQL Server MVP > Thank you for such a fast response. > In the active/active/active/passive configuration is it possible to load [quoted text clipped - 34 lines] >> > If we stay with this configuration will Database mirroring still be an >> > option with the configuration once it is supported by MS. Just so I understand this correctly, if we go with an Active/Active/Active/Passive cluster we would have a setup of at least this, correct? Is the minimum number of instances in this configuration 3? Ex2: (4 nodes - 1 passive = 3 instances split over 3 nodes ) Node A = Instance1 Node B = Instance2 Node C = Instance3 Node D = Passive > SQL Clustering is a failover technology only. It does not load-balance. > [quoted text clipped - 36 lines] > >> > If we stay with this configuration will Database mirroring still be an > >> > option with the configuration once it is supported by MS. You can have however many instances you want as long as you have enough resoruces (disks, IPs, and network names). It's a reasonable design in a four-node cluster to have three SQL2005 instances, each of which runs on a separate node and the 4th node is left as a spare. In addition to configuring where the instances should normally run, you also need to plan/configure the failover behavior. For instane, one design would be for the instance on Node A to failover only to Node D, and do the same for the instances on Node B and Node C. In other words, you designate Node D to be the only and common spare. This design would not give you any HA if Node D fails. But you may consider that as by design. And if this is no good for your requirements, choose a different design. The point is that you need to be explicit about the failover behavior, and communicate that to the users so that hopefully they know what to expect. FWIW, I usually call this a N+1 cluster following the Unix tradition, where N is the umber of 'active nodes' and 1 is the spare. 'Active/Active/Active/Passive' is just too mouthful. Linchi > Just so I understand this correctly, if we go with an > Active/Active/Active/Passive cluster we would have a setup of at least [quoted text clipped - 56 lines] >> >> > an >> >> > option with the configuration once it is supported by MS. I understand that you can have many instances but what is the minimum number of instances for an active/active/active/passive configuration? I assume it is 3, but I thought I would get clarification. > You can have however many instances you want as long as you have enough > resoruces (disks, IPs, and network names). [quoted text clipped - 79 lines] > >> >> > an > >> >> > option with the configuration once it is supported by MS. Well, 'active/active/active/passive configuration' is not really a technical term that everybody agrees to have a common meaning. Intuitively, I guess it's self evident that you are talking about three 'active nodes' plus one 'passive node'. So really there is nothing to clarify. Linchi >I understand that you can have many instances but what is the minimum >number [quoted text clipped - 95 lines] >> >> >> > an >> >> >> > option with the configuration once it is supported by MS. Well, if you want active/active/active/passive, I count 3 distinct SQL instances there (active/active/active). So, yes, the minimum number, in that configuration, would be 3 instances. As Geoff pointed out, if you have 1 instance, it would only run on 1 node and the other 3 nodes would be idle no matter how hard node A was working (Ex2 in your scenarios). -- *mike hodgson* http://sqlnerd.blogspot.com >I understand that you can have many instances but what is the minimum number >of instances for an active/active/active/passive configuration? [quoted text clipped - 103 lines] >> >> Prefect! thanks... > Well, if you want active/active/active/passive, I count 3 distinct SQL > instances there (active/active/active). So, yes, the minimum number, in [quoted text clipped - 113 lines] > >> > >> Hi So if I understood correctly the is no difference between so-called "active/active" config in SQL 2000 and 2005. We still need N independent SQL instances for N active nodes? -- Nick Bobuh Systems Engineer MCT, MCSE, MCSE:M, MCSA, MCSA:M, MCDBA, MCP > Instances are installed to the entire cluster, but can be set to prefer > certain nodes. I personally like N-1 clusters (N nodes, N-1 Instances), [quoted text clipped - 13 lines] > > If we stay with this configuration will Database mirroring still be an > > option with the configuration once it is supported by MS. Yes, Database Mirroring still works. All Database Mirroring requires is that you have at least 2 instances of SQL Server 2005 that are at least Standard Edition. Otherwise, it doesn't care what else is going on. SignatureMike http://www.solidqualitylearning.com Disclaimer: This communication is an original work and represents my sole views on the subject. It does not represent the views of any other person or entity either by inference or direct reference. > We have 4 systems that was initially planned to be joined into an > Active/Active/Active/Passive cluster with SQL 2005. [quoted text clipped - 4 lines] > If we stay with this configuration will Database mirroring still be an > option with the configuration once it is supported by MS. Thanks for address this also... > Yes, Database Mirroring still works. All Database Mirroring requires is > that you have at least 2 instances of SQL Server 2005 that are at least [quoted text clipped - 8 lines] > > If we stay with this configuration will Database mirroring still be an > > option with the configuration once it is supported by MS. |
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