CRM high availability / disaster planning.

Currently we have 1 CRM server and 1 SQL server.

We're running 2003 r2 standard.

We have a mirror setup with our SQL server.

What's would be the ideal way to have CRM mirrored on another machine?  We have a hardware load balancer, would just cloning the machine and giving it a new sid, then having the hardware load balancer do the trick?  or is there a simpler solution like using dns to round robin.  How would we configure the second server?

We're trying to achieve redundancy, where it's a spare that's idle until the first one goes down, or constantly having the load split.

Thanks!

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LegendZMPrincipal Security ArchitectAsked:
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Ted BouskillSenior Software DeveloperCommented:
Microsoft does not offer any load balancing for SQL server, period.  It's the one thing Oracle still holds over them.  There is no way to keep two live SQL databases in perfect sync which is required for true load balancing.

If you want a true hot standby the best way is using an Active/Passive SQL cluster.  What is great about it is that you can flip services to the second server while you upgrade the first!

DNS Round Robin is not appropriate because it simply takes turns flipping traffic to difference IP addresses.  It doesn't know or care if a service is listening on the IP address.  So if one server goes down, DNS has no idea.

Hardware load balancing can at least test the service but it isn't as smart as software load balancing because it doesn't know the true load on the servers or if the service is actually 100% healthy.

I managed a SQL cluster for the backend of our Sharepoint farm and it's outstanding.  The hardware requirements are more complex because you need a SAN device that can share a disk partition with two computers but once it's up it's great.  I hired a contractor to install the cluster and it took him about 4 days including testing.
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LegendZMPrincipal Security ArchitectAuthor Commented:
We have an Equilogic SAN with 2.6 TB. Unfortunately, we cannot do active/passive clustering, because we're running 2003 standard, and SQL 2005 standard.

I guess I'm curious as to how we would setup the CRM redundancy bit, or is that as simple as installing CRM on a machine and pointing it to the same SQL as the production CRM server?



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Ted BouskillSenior Software DeveloperCommented:
Actually if you read the following URLs both do support clustering.  SQL Standard is restricted to clustering two nodes.

http://www.microsoft.com/sql/editions/enterprise/comparison.mspx
http://technet2.microsoft.com/windowsserver/en/library/358b9815-3cd3-4912-a75a-cae85ea8d5ab1033.mspx?mfr=true

If the CRM is a web application then yes you would setup two servers both pointing to the same SQL server and use some time of load balancing to spread the web requests to each.
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LegendZMPrincipal Security ArchitectAuthor Commented:
So I tried setting up both CRM servers with the same volume of the San mapped as the same drive to each one.

I'm not sure if it's working right though,

For example, if on CRM box 1, I add a file to the V:\ drive (the San iSCSI initiated volume) and then go to CRM box 2, the file is not in the V:\ drive.  It seems that the drive information doesn't refresh until the server has been rebooted or the volume re initiated?
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Ted BouskillSenior Software DeveloperCommented:
What mechanism are you using to manage the volume?  Is it clustered?
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LegendZMPrincipal Security ArchitectAuthor Commented:
To manage the SAN we use the equilogic's san interface, we use Microsoft iSCSI initiator to connect to the volume and then bind it as a drive letter

The San is not clustered.
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Ted BouskillSenior Software DeveloperCommented:
Hmm, that behavior sounds like the way a SAN driver for a cluster is supposed to work.  Only one system can control the mapped drive at a time.  I'm not familiar with the Microsoft iSCSI initiator and reading the documentation online didn't make it clear it supported a shared drive like what you are trying.
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LegendZMPrincipal Security ArchitectAuthor Commented:
So then what would be a suggested method to having both CRM IIS servers... well I guess the CRM IIS don't have the SCSI initiators, they just run off the C: drive, and somewhere in the settings they connect by hostname to the sql machine, so if I just imaged the server and renamed it / gave it a new sid, enabled DNS round robin, or some other load balancing mechanism to split requests between the 2 machines, it should work....right?
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Ted BouskillSenior Software DeveloperCommented:
To split requests between the CRM IIS servers all you need to do is setup Network Load Balancing with a virtual IP and a DNS name assigned to the virtual IP.  DNS round robin is basically useless.  DNS round robin cannot detect when one server is offline so users will still get sent to a server that might be down.  Windows NLB is very easy to setup and manage.

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LegendZMPrincipal Security ArchitectAuthor Commented:
So we can use NLB (which i'd prefer to use anyone) But I was under the assumption that Standard edition isn't licensed to use NLB/Clustering features of server 03
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Ted BouskillSenior Software DeveloperCommented:
Standard Network load balancing is free with all versions of Windows.
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