3 queries about active/active and multi-instance

Hi,
1. What is the use of Multiple-Instances of Sql server?
2. If I have only 1 Database, which Mode can I use (Active/Active or
Active/Passive) and why?
3. What is the difference between Active/Active and Active/Passive modes
other than the fact that only Active mode holds the shared device at any
given point of time.
Thanks in advance
Pankaj A. Chitriv
Inline.
joe.
"Pankaj" <pankajchitriv@.rediffmail.com(donotspam)> wrote in message
news:E1CE6DD0-D8A1-4B45-BF58-B309F9BAF770@.microsoft.com...
> Hi,
> 1. What is the use of Multiple-Instances of Sql server?
To run multiple instances of SQL Server in the same machine. Look up
multi-instance in BOL for more info. There are trade-offs to running
multiple instances vs. multiple databases in a single instance. Issues like
administration, security, isolation, memory management, real memory size,
etc... are just some that you need to be aware of.

> 2. If I have only 1 Database, which Mode can I use (Active/Active or
> Active/Passive) and why?
Active/passive. A SQL Server database can be driven by 1 and only 1
instance/engine at any time. It is a shared nothing architecture. Suggest
you review MS failover clustering concepts to get a better feel of how this
works. The term active/active really is kind of a marketing term. It really
means both machines are actively doing work on different databases, not both
machines are servicing the same database.
Btw, active/active and active/passive are actually obsolete terms since SQL
Server does support up to 8 nodes now and up to16 instances (not hard limit
but good luck with PSS if you go beyond). Multiple instance cluster is more
appropriate especially when you get into large clusters.

> 3. What is the difference between Active/Active and Active/Passive modes
> other than the fact that only Active mode holds the shared device at any
> given point of time.
Once you understand what active/active and active/passive mean in the SQL
Server world, this will become very clear. That aside, there are significant
considerations for configuration when you have multiple active nodes in a
cluster. You have to be smart about resource allocation and management and
failover strategies.

> Thanks in advance
> Pankaj A. Chitriv
|||Thanks Joe.
Regards
Pankaj
"joe." wrote:

> Inline.
>
> joe.
> "Pankaj" <pankajchitriv@.rediffmail.com(donotspam)> wrote in message
> news:E1CE6DD0-D8A1-4B45-BF58-B309F9BAF770@.microsoft.com...
> To run multiple instances of SQL Server in the same machine. Look up
> multi-instance in BOL for more info. There are trade-offs to running
> multiple instances vs. multiple databases in a single instance. Issues like
> administration, security, isolation, memory management, real memory size,
> etc... are just some that you need to be aware of.
> Active/passive. A SQL Server database can be driven by 1 and only 1
> instance/engine at any time. It is a shared nothing architecture. Suggest
> you review MS failover clustering concepts to get a better feel of how this
> works. The term active/active really is kind of a marketing term. It really
> means both machines are actively doing work on different databases, not both
> machines are servicing the same database.
> Btw, active/active and active/passive are actually obsolete terms since SQL
> Server does support up to 8 nodes now and up to16 instances (not hard limit
> but good luck with PSS if you go beyond). Multiple instance cluster is more
> appropriate especially when you get into large clusters.
> Once you understand what active/active and active/passive mean in the SQL
> Server world, this will become very clear. That aside, there are significant
> considerations for configuration when you have multiple active nodes in a
> cluster. You have to be smart about resource allocation and management and
> failover strategies.
>
>