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Default and Maximum Values of MAXDATAFILES, MAXLOGFILES, MAXLOGMEMBERS, MAXINSTA

原创 Linux操作系统 作者:tolywang 时间:2007-07-26 00:00:00 0 删除 编辑
FREQUENTLY ASKED QUESTIONS
--------------------------

NOTE:
-----
All questions are related to Oracle for z/OS (OS/390), and the answers are
valid for Oracle8, Orale8i, Oracle9i and Oracle10g.


CONTENTS
--------
1. What are the maximun number of datafiles ? MAXDATAFILES
2. What are the maximun number of redolog groups ? MAXLOGFILES
3. What are the maximun number of members for a redolog group ? MAXLOGMEMBERS
4. What are the maximun number of instances that can access a database concurrently? MAXINSTANCES
5. What are the maximun number of redo log files that can be recorded in the log history of the
control file? MAXLOGHISTORY


1. MAXDATAFILE

Maxdatafiles can be defined when the database is created or when the controlfile is recreated.
The default valueis 32, the maximun value is 4096 per tablespace

In 8.0 and 8i, the limit on datafiles per database is around 40,000. This limit is
imposed by the limit on control file size (20,000 blocks) with a 4K block size.

In 9i and 10g, larger block sizes are supported, thus with DB_BLOCK_SIZE=8192 there can be
up to 65,534 datafiles (same limit as other platforms).

However, there is an issue with the maximum number of files the server can have
open simultaneously. In both the OSDI and MPM implementations the server is
limited to approximately 3000 distinct simultaneously open files across all
sessions. This limit is removed in Oracle9i 9.2.


2. MAXLOGFILES

MaxLogFiles can be defined when the database is created or when the controlfile is recreated.
The default value, if not especified, is 32, and the maximun value is 256.


3. MAXLOGMEMBERS

MaxLogMembers can be defined when the database is created or when the controlfile is recreated.
The default value, if not especified, is 2, and the maximun value is 5.


In Oracle10g, now you can also specify the following parameters:

4. MAXINSTANCES

The MAXINSTANCES option of CREATE DATABASE limits the number of instances that can access a database concurrently.
The default value for this option under z/OS is 15. Set MAXINSTANCES to a value greater than the
maximum number of instances you expect to run concurrently.


5. MAXLOGHISTORY

The MAXLOGHISTORY option of CREATE DATABASE specifies the maximum number of redo log files that can be recorded in the log
history of the control file. The log history is used for automatic media recovery of
Oracle Real Application Clusters.
For Oracle Real Application Clusters, set MAXLOGHISTORY to a large value, such
as 100. The control file can then store information about this number of redo log
files. When the log history exceeds this limit, the Oracle server overwrites the oldest
entries in the log history.
Setting the MAXLOGHISTORY to 0 (zero), disables log history.


Here is what you can find in Oracle8, 8i and 9i System Administration guide manual for Oracle for OS/390.

Parameter Default Maximum Valid Range
MAXDATAFILES 32 4094 N/A
MAXINSTANCES N/A N/A N/A
MAXLOGFILES 32 256 2 - 256
MAXLOGMEMBERS 2 5 N/A
MAXLOGHISTORY N/A N/A N/A

Here is what you can find in Oracle10g System Administration guide manual for Oracle for z/OS (OS/390).

Parameter Default Maximum Valid Range
MAXDATAFILES 32 655342 N/A
MAXINSTANCES 1 15 N/A
MAXLOGFILES 32 256 N/A
MAXLOGMEMBERS 2 5 N/A
MAXLOGHISTORY 100 65534 N/A


References
----------
This information is found in any of the next manuals.

Oracle8 Enterprise Edition for OS/390
System Administration Guide
Appendix B Operating System Dependent Variables B-5

Oracle8i Enterprise Edition for OS/390
System Administration Guide
Appendix B Operating System Dependent Variables B-5

Oracle9i Enterprise Edition
System Administration Guide
Release 1 (9.0.1) for OS/390
Part No. A89899-01
Appendix B Operating System Dependent Variables B-4

Oracle® Database
System Administration Guide
10g Release 2 (10.2) for IBM z/OS (OS/390)
B25398-01
Appendix B Operating System Dependent Variables B-6


Keywords:
---------
MAXDATAFILES MAXLOGFILES MAXLOGMEMBERS MAXINSTANCES MAXLOGHISTORY MVS OS/390 LIMITS MAXIMUN

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