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Talking about DB2 Zos-DB2 LUW VS DB2 Zos

Overview:

You may know more about DB2 LUW, but little about DB2 Zos (mainframe operating system), because the internal information of IBM has always been relatively closed, especially for products that we rarely see in the market, such as Zos operating system, generally speaking, they are only accessible to bank staff and IBM employees, and the circle is relatively small.

This sharing mainly compares DB2 LUW with DB2 for Zos to help us quickly understand the architecture of mainframe DB2.

Introduction to DB2 Zos:

Under the Z/os operating system, multiple DB2 subsystems can be run at the same time, and each subsystem corresponds to a set of DB2 address spaces (Address Space): ssnmMSTR, ssnmDBM1, ssnmDIST, ssnmSPAS, ssnmWLM, ssnmIRLM, in which the ssnm is SUBSYSTEM NAME.

A DB2 subsystem mainly consists of the following three address spaces

DBM1 (DATABASE ADDRESS SPACE):

Provides the address space of database services, including SQL Process and Buffer manage,Bind.

MSTR (SYSTEM SERVICE ADDRESS SPACE):

Provide address space for system services and perform various system-related functions

There are mainly Thread management, Log management, Checkpoint and Trace.

IRLM (INTERNAL RESOURCE LOCK MANAGER):

Provides the address space for internal resource locking management, namely Lock Management.

Use the DB2 command "START DB2" to start these address spaces.

For example, you can see BB1AIRLM, BB1AMSTR, BB1ADBM1 in the SD.DA produced.

Comparison of DB2 LUW and DB2 Zos:

The following figure shows the architecture of DB2 LUW. You can see that the entire NODE (a computer in the network) on the server contains two instances INST1 and INST2, each containing two DB001,DB002 (DB003,DB004), and each database contains three tablespaces (catalog, tempspace1, userspace1). There are database-level configuration files and log files (DB Config, LOGS) in each database. The entire instance also has an instance-level configuration file, and the client can connect to the server.

The following figure is the architecture diagram of DB2 for Zos, the entire server LPAR (host virtual computer) contains two subsystems (DB7G, DB8G, equivalent to the instance in the distributed platform), each subsystem contains four system databases (DSNDB*), a user database (DB001), and the user database contains a user tablespace. There are log files and BSDS files at the entire subsystem level. The entire subsystem has configuration files at the subsystem level. The client can connect to the server through DB2 CONNECT and DDF (Distributed Data Facility).

In the following figure, by comparing the differences between the DB2 of ZOS and LUW, we can see that some of them are tablespace attributes in LUW and replaced by database attributes in ZOS.

Let's briefly introduce several important databases in ZOS:

DIRECTORY DATABASE (DSNDB01) consists of a series of Tablespace, which contains the Control Block and status information needed for the normal operation of the DB2. You cannot use SQL statements to access the DIRECTORY.

It includes the following Tablespace:

DBD01 DATABASE DESCRIPTOR TABLESPACE, which holds the internal descriptor of all Database defined in the DB2 system, that is, DBD, is the internal description of all objects in DB2.

SCT02 SKELETON CURSOR TABLESPACE, including information about the access path of DBRM, the internal form of the SQL statement of the application, and so on. Every time a PLAN,DB2 is Bind, a Skeleton Cusor Table is created in the SCT02.

SPT01 SKELETON PACKAGE TABLESPACE, including information about the access path of PACKAGE, the internal form of the SQL statement of the application, and so on. Every time a PACKAGE,DB2 is Bind, a SKELETON PACKAGE TABLE is created in the SPT01.

SYSUTILX SYSTEM UTILITIES TABLESPACE, every Utility running in DB2, has a record in SYSUTILIX to describe the status information of the Utility. This record is deleted after the normal termination or termination of the Utility, but is not deleted for abnormally stopped Utility. This record is used when restarting an abnormally stopped UTILTIY.

SYSLGRNX LOG RANGE TABLESPACE, record Tablespace

The Log RBA value of Indexspace and Partition in Open and Close.

DB2's CATALOG DATABASE (DSNDB06) consists of a series of Table that records information about all the Object defined in the DB2, which can be manipulated using SQL statements. These system tables are called 'SYSIBM.SYS*'.

The DSNDB06 mainly contains the following:

All defined by Data Definition Language (DDL)

Object of

Application Package

Application Plan

All authorized users and their scope of authority

The name of Image Copy Dataset and the volume it belongs to

DSNDB04 is defined when installing the DB2 subsystem. If the user does not specify Database when creating Table or Tablespace, the system automatically specifies the default Database-DSNDB04, the default Buffer Pool is BP0, and the default Storage Group is SYSDEFLT.

In addition, we need to know something about DB2I. Proficient in the use of DB2I, basically can solve the simple zos operation and maintenance.

DB2I is an interactive application tool provided by DB2 system on 9000 system. In DB2I, users can execute arbitrary SQL statements, automatically generate database table structure definition, prepare user programs, precompile user programs, BI ND plans or packages, execute user programs, execute DB2 commands, and run DB2 tool programs. DB2I is a tool often used by DB2 developers. Here we give a brief introduction to some of the features that are often used.

Here is the initial picture of DB2I:

The functions of each option are:

1 SPUFI is used to write SQL statements and run them to produce results

2 DCLGEN automatically generates table structures in different languages and definitions of host languages

3 PROGRAM PREPARATI ON completes the program by inputting various parameters needed by the preparation program through multi-layer screen.

Precompile, compile, pre-connect, connect and execute each step of the sequence

4 PRECOMPI LE precompiles the source program by inputting the necessary parameters through the screen

5 BI ND/ REBI ND/ FREE bind, rebind, or release plan or package

6 RUN executes SQL program

7 DB2 COMMANDS executes the DB2 command

8 UTI LI TI ES executes other DB2 tool programs

D DB2I DEFAULTS sets global parameters

X EXI T exit

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