All SQL Server 2000 customers should have upgraded their production systems to Service Pack 3 (SP3) by now for protection against the Slammer worm and other security vulnerabilities. But Microsoft recently released SP3a without much fanfare. What does SP3a address and who needs to upgrade to it? Microsoft's original Web page describing SP3a didn't specify what new features the service pack included or whether you needed to apply SP3a if you were already using SP3. However, Microsoft has now provided clearer answers to these questions on the SP3a download site.

SP3a replaces SP3, which is no longer available from Microsoft. You can download SP3a at http://www.microsoft.com/sql/downloads/2000/sp3.asp. If you haven't already installed SP3, you should upgrade to SP3a, but Microsoft says that no serious security problems require you to deploy SP3a if you're already using SP3.

The SP3a download site is still a bit confusing, implying that some features available in SP3 are brand-new in SP3a. Microsoft says that only three features are new in SP3a: SP3a lets you apply service-pack upgrades to SQL Server 2000 Evaluation Edition, contains a new version of Microsoft Data Access Components (MDAC), and disables listening on port 1434 when networking is disabled. The other features listed under "Benefits" on the download site were already released in SP3. (To read about the problems that the new MDAC version solves, see the Microsoft articles "FIX: SQL Server Does Not Start and an Access Violation Occurs After You Install SQL Server 2000 Service Pack 3," http://support.microsoft.com/?kbid=814572, and "FIX-Performance Degradation and Memory Leak in the SQL Server ODBC Driver," http://support.microsoft.com/?kbid=814410.)

Figuring out which service-pack version you're running—SP3 or SP3a—can be confusing. The downloadable files for SP3a and SP3 have the same names, the build numbers for both packs are the same in most cases, and ServerProperty('ProductLevel') reports "SP3" for both versions. However, you can distinguish between versions by looking at the version number of the Net-Library file ssnetlib.dll. The readme.txt file for SP3a says that this file's version number will be 2000.80.760.0 for SP3 and 2000.80.766.0 for SP3a. I hope Microsoft makes it easier to tell service-pack versions apart in the future.