Quick Beginnings

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Memory requirements

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At a minimum, DB2 Universal Database (UDB) requires 256 MB of RAM. For |a system running just DB2 UDB and the DB2 GUI tools, a minimum of 512MB of |RAM memory is required. However, 1GB of RAM memory is recommended for improved |performance. These requirements do not include any additional memory requirements |for other software that is running on your system.

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When determining memory requirements, be aware of the following:

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Clarification of DB2 UDB client support

The "DB2 clients" topic in the 8.1 version of the DB2 Quick Beginnings for Clients guide states the following:

DB2 clients can connect to DB2 servers two releases later or one release earlier than the client's release level, as well as to servers at the same release level.

An amendment to that statement is as follows:

While connections from Version N clients to Version N + 2 servers is possible in some environments, this is a supported configuration as long as Version N is in service. Once Version N is withdrawn from service, this configuration is no longer supported.

DB2 Version 7 clients connecting to a DB2 Version 8 server is no longer supported because DB2 Version 7 has been withdrawn from service.

Modifying kernel parameters (Linux)

Before installing DB2 UDB, you should consider updating your Linux kernel parameters. DB2 Universal Database (UDB) automatically raises the IPC limits where necessary. You might want to raise these limits higher depending on your particular needs.

Prerequisites

You must have root authority to modify kernel parameters.

Procedure

To update kernel parameters:

Red Hat and SuSE
Systems using a 2.4.x series kernel have a default value for the message queue parameter (msgmni), which allows only a few simultaneous connections to DB2 UDB. Semaphore array parameters also have to be changed for DB2 UDB to run successfully. To check shared memory segment, semaphore array, and message queue limits, issue the ipcs -l command.

The following output is from the ipcs -l command.

   # ipcs -l

------ Shared Memory Limits --------
max number of segments = 4096              // SHMMNI
max seg size (kbytes) = 262144             // SHMMAX
max total shared memory (kbytes) = 8388608 // SHMALL
min seg size (bytes) = 1

------ Semaphore Limits --------
max number of arrays = 1024                // SEMMNI
max semaphores per array = 250
max semaphores system wide = 256000
max ops per semop call = 32
semaphore max value = 32767

------ Messages: Limits --------
max queues system wide = 1024              // MSGMNI
max size of message (bytes) = 65535        // MSGMAX
default max size of queue (bytes) = 16384  // MSGMNB

where 

  max semaphores system wide = 
  max number of arrays x max semaphores/array

For 32-bit Linux kernels, modify the kernel parameters by adding the following entries to the default system control configuration file, /etc/sysctl.conf: 

  kernel.msgmni = 1024
  kernel.sem = "250 256000  32 1024"
  kernel.shmmax=268435456

For 64-bit Linux kernels, modify the kernel parameters by adding the following entries to the default system control configuration file, /etc/sysctl.conf: 

  kernel.msgmni = 1024
  kernel.sem = "250 256000  32 1024"
  kernel.shmmax=1073741824

Run sysctl with the -p parameter to load in sysctl settings from the default file /etc/sysctl.conf: 

   sysctl -p

The entries from the sysctl.conf file are read during startup by the network initialization script.

On some distributions you might be required to add sysctl -p in one of the system initialization files, such as rc.local, so that kernel parameters are set after each restart.

Modifying kernel parameters (Solaris Operating Environment)

The following information is an amendment to the "Modifying kernel parameters (Solaris Operating Environment)" topic in the Quick Beginnings for DB2 Servers guide:

For DB2 Universal Database (UDB) to operate properly, it is recommended that you update your system's kernel configuration parameters. You can use the db2osconf utility to suggest recommended kernel parameters.

To use the db2osconf command, you must first install DB2 UDB. The db2osconf utility can only be run from $DB2DIR/bin.

You must restart your system after modifying kernel parameters.

DB2 Universal Database Express Edition Version 8.2 Basics manual available for download

IBM DB2 Universal Database Express (DB2 UDB Express) is the newest member of the DB2 Universal Database Version 8 product family. It combines the power, function, and reliability of the IBM award-winning DB2 UDB relational database with simplicity in packaging, installation, and deployment at a minimal investment cost to meet the data management needs of small and medium businesses.

DB2 UDB Express is designed for customers with minimal in-house database skills who need an easy-to-install database integrated into their application software solutions. It is a multi-user version of DB2 UDB that supports local and remote applications in stand-alone and local area network (LAN) environments.

For further information on DB2 UDB Express, download Quick Beginnings for DB2 Express Edition and DB2 Universal Database Express Edition Version 8.2 Basics from the DB2 UDB product manuals Web page at http://www.ibm.com/software/data/db2/udb/support/manualsv8.html

Verifying that your databases are ready for migration

The following prerequisites section is documented in the 8.2 version of the topic that explains how to verify that your databases are ready for migration:

Prerequisites
Ensure that the migration.log file, found in the instance owner's home directory, contains the following text: Version of DB2CKMIG being run: VERSION 8.

This prerequisite is in fact a post-migration step performed at the end of the procedure.

Common Criteria certification for DB2 UDB

The authoritative information for DB2(R) UDB configurations that have been certified for Common Criteria can be found at http://niap.nist.gov/cc-scheme

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