What are "Cumulative Special Build" in fixpack download web page?

Question

On our computers Db2 v11.5.8.0 Linux/x86-64 is installed. I would like to install new fixes as regular update, specially to deploy security fixes.

Couple of weeks ago new fixpack 11.5.9.0 was released. But now I see Cumulative Special Build is listed on Download Db2 fixpack web page too. Looking into detail of CSB web page, there is info: "CSB are cumulative, each CSB contains all fixes delivered in previous CSB." If I understand correctly, CSB should not be installed on top of v11.5.9.0, but on top of previous CSB (if installed at all on Db2 server). Is this correct?

What is the purpose of CSB in the first place? To only contain security and failure fixes without new features? What is the release of Db2 after applying CSB?

Thanks

Answer 1

Think of CSBs like "interim" fixpacks. They contain all of the fixes (APARs) that have been released since a modpack (or fixpack) was released. They are released much more frequently than modpacks or fixpacks -- almost monthly.

They look like a special build when they are installed:

$ db2level
DB21085I  This instance or install (instance name, where applicable:
"db2inst1") uses "64" bits and DB2 code release "SQL11059" with level
identifier "060A010F".
Informational tokens are "DB2 v11.5.9.0", "special_37108",
"DYN2311080756AMD64_37108", and Fix Pack "0".
Product is installed at "/opt/ibm/db2/V11.5".

As I understand it, CSBs go through more testing (not as much as a full modpack / fixpack, but more than the old Special Builds).

CSBs are built on top of a specific modpack / fixpack, so there are currently CSBs being generated for both Db2 11.5.8.0 and Db2 11.5.9.0.