在IBM上查到：
DB2 v8.1由于java虛擬機版本不被支持，所以安裝使用db2setup無法安裝。翻譯并記錄下來
Red Hat Enterprise Linux好像支持jvm 在1.4.1以上，因此需要替換v8.1安裝介質中的jvm.建議：IBM version of the Java SDK 1.4.1(我使用的是Sun SDK 1.4.2_04分為兩個步驟：1. java SDK 安裝。2. DB2安裝)
java SDK
- 下載SDK (sun,ibm都有，具體網址忘了，以后再補吧）
- 安裝SDK rpm -ivh j2sdk-1_4_2_04-linux-i586-rpm (我下的是：j2sdk-1_4_2_04-linux-i586-rpm.bin 在linux下拷貝到本機，運行：./j2sdk-1_4_2_04-linux-i586-rpm.bin。然后rpm安裝即可)
- 修改/etc/profile文件,配置java路徑(包括JAVA_HOME、CLASSPATH、path）注意大小寫。
DB2
- copy 介質到硬盤上，主要目的是可以修改自帶的jvm (如: cp -R /media/cdrom/* <temporary_directory>)
- 刪除 db2/linux/java 的目錄 (如: rm -Rf <temporary_directory>/db2/linux/java)
- 創建“java”link指到Java1.4.1的目錄 (如.: ln -s /opt/IBMJava2-141 /<temporary_directory>/db2/linux/java)
- 安裝了... (e.g.: <temporary_directory>/db2setup)
IBM原文：（http://www-306.ibm.com/software/data/db2/linux/validate/rhel3faq.html）
Yes, there is a workaround. However it is not officially supported by IBM and is therefore provided for informational purposes only. You could use IBM's version of the Java 1.4.1 environment instead of 1.3.1 that is shipped with the DB2 install image. Note that IBM does not support either 1.3.1 or 1.4.1 (SR1) on RHEL 3 yet. To use this unsupported workaround, you first need to install the IBM version of the Java SDK 1.4.1. Depending on which version of the DB2 install image/CD you have, perform the following steps.
If you have a DB2 UDB V8.1 GA (or level prior to 8.1.4) install image/CD:
- Copy its contents to the hard disk (e.g.: cp -R /media/cdrom/* <temporary_directory>) where the <temporary_directory> is large enough to hold the install image.
- Delete the db2/linux/java sub-directory.
(e.g.: rm -Rf <temporary_directory>/db2/linux/java)
- Create a symbolic link called java to point to the Java 1.4.1 directory.
(e.g.: ln -s /opt/IBMJava2-141 /<temporary_directory>/db2/linux/java)
- Ensure the DISPLAY is exported properly and launch the installer.
(e.g.: <temporary_directory>/db2setup)
If you have DB2 install image / CD refreshed at Version 8.1.4 or later:
- Set the following environment variables: export DB2USELOCALJRE=TRUE
export JAVA_HOME=<path to 1.4.1 JVM>
(e.g.: export JAVA_HOME=/opt/IBMJava2-141)
- Launch db2setup from the same shell