We get several calls related to setup and installation questions. One such common question is related to installation of SQL 2000 and SQL 2005 on the same box.

Through this blog, we will try to address these commonly asked questions.

You can install SQL 2000, SQL 7.0 and SQL 2005 on the same box. However, there are certain special considerations that you should be aware of.

First, refer to this comparison sheet published by Microsoft at the MSDN website.

This sheet can be used as a handy reference to decide if your planned configuration is supported or not.

Now, let’s look at some of the specific scenarios.

Standalone Installations

• x86 hardware running 32-bit OS 
  You can install SQL 2005 32-bit edition side-by-side with SQL 2000 32-bit edition.
  
  If SQL 2000 is already installed, make sure that its service pack is either SP3 or SP4, before you attempt to install SQL 2005. 
  
  SQL 2005 can be at RTM, but you might want to consider moving to SP1.
   
• x64 hardware running x64 OS
  You can install SQL 2005 x64 edition side-  by-side with SQL 2000 32-bit edition. Remember that there is no native SQL 2000 x64 edition.
  
  In this situation, you MUST apply SP4 on SQL 2000 instances. This is because SQL 2000 32-bit support on x64 bit hardware running Windows Server 2003 SP1 was added only in SP4.
      
• IA64 hardware running IA64 OS
  You can install SQL 2005 IA64 edition side-by-side with SQL 2000 IA64 edition. SQL Server 32-bit editions are not supported on IA64 bit hardware.
  
  SQL 2000 IA64 edition was released in tandem with SQL Server 2000 Service Pack 3 (SP3).    

Emphasizing the need for SP3 or SP4

If you want to install SQL 2005 and SQL 2000 on the same box, you must patch SQL 2000 to SP3 or above. Let me explain why.

In SQL Server 2000, the identification of the server connection endpoints is performed by the SQL Server service. SQL Server 2005 replaces that function with the SQL Server Browser service.

In case you have SQL 2000 already installed, the SQL Server Service is will listen at UDP port 1434. However, when you install SQL 2005 on the same box, the SQL Browser service will wait for 5 seconds for SQL 2000 to relinquish port 1434.

With SQL 2000 SP3 and above, this works fine. However, versions earlier than SP3 do not properly share port 1434 and may not make your instances of SQL Server available to requesting client applications. The SQL Server Browser might fail to start in instances running on less than SP3.

To resolve this problem with versions of SQL Server 2000 earlier than Service Pack 3, stop SQL Server 2000, start SQL Server Browser, then restart SQL Server 2000. The SQL Server 2000 listener service continues to attempt to start on port 1434; therefore, the instance of SQL Server 2000 should be upgraded to Service Pack 3 as soon as possible.

SQL Server 7.0 has no similar capabilities and has no conflicts with SQL Server Browser.

Cluster installations

Pretty much the same, but with some special consideations.

• If you are running a 32-bit OS on x86 hardware based cluster, you can install SQL 2005 32-bit edition side-by-side with SQL 2000 32-bit edition. Again, you must install SP3 or above for SQL 2000.
   
• To the above cluster, you cannot to add another node which is running on x64 hardware. This is not supported.
   
• If you are running a x64 hardware with x64-bit OS based cluster 

·         You can install SQL 2005 x64-bit edition with SQL 2000 32-bit edition with SP4

·         You can install SQL 2005 32-bit edition with SQL 2005 x64-bit edition
           

• For an IA64 hardware based cluster running IA64 bit OS, you can only install SQL 2005 IA64-bit edition with SQL 2000 IA64-bit edition.          

References

For more information on SP3, refer to our blog here. More information on SP4 can be found here.

Information on SQL 2005 SP1 and its hotfix rollup 2153 can be found here.

Cheers!