75 ways to demystify DB2 #75: Techtip : How to recover from a DB2 bug which removes the installed files?

Body

Installfixpack takes a backup of the existing installation files and then starts the installation of the new binaries, if there is a major error failure at some point during the installation of the new binaries, the deployed new binaries are rolled backed and the backup of the old files is restored. In this particular case were db2chgpath is failing inside installfixpack the rollback of the deployed new files happens but the restore of the backup is not happening therefore the files go missing. This problem is addressed via below APARs.

DB2 V10.1 : APAR IT02887 : First Fixed in DB2 V10.1FP5
DB2 V10.5 : APAR IT04436 : First Fixed in DB2 V10.5FP5
 

Now, how do we recover from this mess?
Lets say we hit this bug when installing a special build X on top of db2level db2_v105fp3 then we have few options :
1) Reinstall db2 (db2_v105fp3) in the same path and re-apply special build X on top of that.
2) Directly install special build X using "-f db2lib" option of installFixPack command.
3) If its DPF environment then other option is copy all the binary files from the other physical machines over to problematic machine and reinstall special build X.