We are looking at having a multi-instance cluster for an
application instead of having 2 clusters for one
application. First I need any information on why we
should go with one cluster with multi-instance instead of
two clusters each with one instance. Also one of the
clusters is already setup and is in testing now. As I
understand it we would need different drives for the data
and logs. Both instances can not reside on the same
drive. Also I understand that all I will have to do is to
install another instance of SQL Server on the cluster
inorder to make this a multi-instance cluster. Any
informaiton on this subject would be very helpful.

Consider using an Active/Active cluster. Each will have its own instance
and can act as a backup for the other. Just make sure to have enough RAM.

--
Tom

---------------------------------------------------------------
Thomas A. Moreau, BSc, PhD, MCSE, MCDBA
SQL Server MVP
Columnist, SQL Server Professional
Toronto, ON Canada
www.pinnaclepublishing.com/sql


"ash" <anonymous (AT) discussions (DOT) rr.com> wrote

We are looking at having a multi-instance cluster for an
application instead of having 2 clusters for one
application. First I need any information on why we
should go with one cluster with multi-instance instead of
two clusters each with one instance. Also one of the
clusters is already setup and is in testing now. As I
understand it we would need different drives for the data
and logs. Both instances can not reside on the same
drive. Also I understand that all I will have to do is to
install another instance of SQL Server on the cluster
inorder to make this a multi-instance cluster. Any
informaiton on this subject would be very helpful.

Multiple-instance clusters are a good way to maximize resources, especially
now that Windows Server 2003 supports more than two nodes on a cluster. I
like an N-1 setup where you have N nodes and N-1 instances. That way you
have a standby system for any cluster node failure and the cost savings are
obvious.


--
Geoff N. Hiten
Microsoft SQL Server MVP
Senior Database Administrator
Careerbuilder.com




"ash" <anonymous (AT) discussions (DOT) rr.com> wrote

The only difference I see between an active/active and a
multi-instance cluster is that the active/active is each
server has an instance of SQL Server running on it. The
Multi-instance is just saying you have multi instance of
SQL server running at the same time.

From the BOL:

Multiple Instances of SQL Server on a Failover Cluster
You can run only one instance of SQL Server on each virtual server of a SQL
Server failover cluster, although you can install up to 16 virtual servers
on a failover cluster. The instance can be either a default instance or a
named instance. The virtual server looks like a single computer to
applications connecting to that instance of SQL Server. When applications
connect to the virtual server, they use the same convention as when
connecting to any instance of SQL Server; they specify the virtual server
name of the cluster and the optional instance name (only needed for named
instances): virtualservername\instancename. For more information about
clustering, see Failover Clustering Architecture.


Because you're sharing resources on an Active/Passive cluster, I'd tend to
go with Active/Active, if I were going to install two instances.


--
Tom

---------------------------------------------------------------
Thomas A. Moreau, BSc, PhD, MCSE, MCDBA
SQL Server MVP
Columnist, SQL Server Professional
Toronto, ON Canada
www.pinnaclepublishing.com/sql


"ash" <anonymous (AT) discussions (DOT) microsoft.com> wrote

The only difference I see between an active/active and a
multi-instance cluster is that the active/active is each
server has an instance of SQL Server running on it. The
Multi-instance is just saying you have multi instance of
SQL server running at the same time.

What my goal is to lessen the amount of servers we have on
our floor. First the server one server is already in
use. Lets say the sql server name is server1 and now what
I want to do, if possible, is install another sql server
named server2. There for I have two instances of sql
server running. One will be running on physical node one
and the other instance will be running on physical node
two. But if I understand correctly both will have
different vitrual names. Both can fail over to the other
node and both and live on the same node at the same time.
Is this what Active/Active is? Thanks for all your help
and time.

Yep. That's Active/Active.

--
Tom

---------------------------------------------------------------
Thomas A. Moreau, BSc, PhD, MCSE, MCDBA
SQL Server MVP
Columnist, SQL Server Professional
Toronto, ON Canada
www.pinnaclepublishing.com/sql


"ash" <anonymous (AT) discussions (DOT) microsoft.com> wrote

What my goal is to lessen the amount of servers we have on
our floor. First the server one server is already in
use. Lets say the sql server name is server1 and now what
I want to do, if possible, is install another sql server
named server2. There for I have two instances of sql
server running. One will be running on physical node one
and the other instance will be running on physical node
two. But if I understand correctly both will have
different vitrual names. Both can fail over to the other
node and both and live on the same node at the same time.
Is this what Active/Active is? Thanks for all your help
and time.

"ash" <anonymous (AT) discussions (DOT) rr.com> wrote


Pros :
- No need to change application code (i.e. connection string)
- Assuming active / passive you do not need to design your server
resources. For example, if both nodes are 70% CPU than a failover
where both will be running on the same node will cause a 100% CPU.

Cons :
- Hardware price.
- Software price (e.g. OS license for the passive node)

---------
active/active (multi instance cluster)
Pros :
- you save two nodes (assuming that you run on win 2000)

Cons :
- you have to change the application code
- you have to plan the server load in case of failover.

A middle way is to use 2:1 cluster
------
Tomer Meshorer
Database Engineer
Polyserve (http://www.polyserve.com/sql)
tmeshorer (AT) polyserve (DOT) com

The terminology is not active/active anymore; it was
changed post-SQL 2K release by MS. It was changed to
multiple instance cluster, as that is what it is.
Active/active stems from SQL 7 because you could have at
most 2 active SQL Servers. With SQL 2K, it's up to 16.

That change in terminology hasn't really gotten across in practice even in
the DBA community, let alone in the IT management circle. I used to fight
the use of 'Active/Active' or 'Active/Passive.' But then I realized that the
terminology is so pervasive in everyday conversation regarding failover
clusters that resistance is futile. Besides, it does succinctly summarizes
how the nodes are being utilized. The term 'multiple instance cluster'
doesn't convey any information on the node usage.

--
Linchi Shea
linchi_shea (AT) NOSPAMml (DOT) com


"Allan Hirt" <allanh (AT) NOSPAMavanade (DOT) com> wrote