February 25, 2003 at 9:29 am
I am involved in a project where 5 SQL Server instances will be running on a cluster. I need to know what happens if one instance fails, will all of the instances fail over. I need to know this so that we get the disk configured correctly. I cant find any reference to this in the microsoft docs.
Can anybody help ?
Tom Willetts
February 25, 2003 at 9:45 am
Each instance depends on its own resources and one instance fails doesn't affect the rest instances. If two or more instances share same physical resources such as same disks, the disks fail will affect these instances that depend on the same disks.
You have to carefully plan the system resources, for example, memory, disks so each instances do not interfere each other for same resources.
MSDTC and Search service will be shared by all instances.
February 25, 2003 at 11:02 am
Are you running the instances on a Virtual Server or are you running them on the actual nodes? Most likely you are running them on one or more virtual servers.
When your currently running node fails, the cluster fails over to the other node and that node takes control of the virtual servers (so in effect, they fail over also). I have a 2-node active/passive cluster with two virtual servers for my MS SQL Server 2000 databases. In cluster manager, I have four cluster groups:
1. the cluster itself (services, etc)
2. my backup software
3. my first virtual server
4. my second virtual server
None of the groups are dependant on another, which means that I can fail one group over and the rest won't automatically failover. However, if my current node fails (shutdown, whatever) ALL of my cluster groups automatically fail over to the alternate node's control.
Hope that answered your question.
-SQLBill
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