DB_FILE_SIMULTANEOUS_WRITES
by Brian Laskey, David C. Kreines
Oracle Database Administration: The Essential Refe
- Dedication
- Preface
- I. DBA Tasks
- 1. Introduction
- 2. Installation
- 3. Maximizing Oracle Performance
- 4. Preventing Data Loss
- 5. Oracle Networking
- Oracle Names
- MultiProtocol Interchange
- Connecting to Non-Oracle Databases
- Network Manager Data Storage
- Using Network Manager
- Files Created by Network Manager
- Oracle Net8 Assistant
- Manual Network Configuration
- Sample SQL*Net Files
- SQL*Net Troubleshooting
- 6. Security and Monitoring
- 7. Auditing
- 8. Query Optimization
- 9. Oracle Tools
- 10. The Oracle Instance
- 11. The Oracle Database
- 12. Initialization Parameters
- 13. SQL Statements for the DBA
- SQL Commands by Task
- SQL Command Syntax
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- column_constraint_clause
- auto_extend_clause
- for_clause
- filespec
- autoextend_clause
- global_index_clause
- local_index_clause
- table_constraint_clause
- table_ref_clause
- column_ref_clause
- column_constraint_clause
- index_organization_clause
- segment_attrib_clause
- partition_clause
- autoextend_clause
- 14. The Oracle Data Dictionary
- Static Data Dictionary Views
- Dynamic Performance Data Dictionary Views
- 15. System Privileges and Initial Roles
- 16. Tools and Utilities
Name
DB_FILE_SIMULTANEOUS_WRITES
Synopsis
Values:1 to 4 × number of disks in a striped file, or 4 if no striping
Default:4
Specifies the maximum number of simultaneous writes allowed for a given database file. Oracle also uses this parameter to compute various internal parameters that affect read and write operations to database files. Increasing the value of this parameter is beneficial in environments where the database files reside on RAM devices or which use disk striping at the operating system level. If striped files are used, Oracle recommends that the value of this parameter be set to four times the maximum number of disks in the file that is striped the most. This parameter is also used to determine the number of reads per file in the redo read-ahead when reading redo during recovery.
Warning
If an excessively large value is specified for this parameter, significant delays in performing read and write operations to a given database file might occur, because I/O requests get queued in the disk. If the value set is too small, the number of I/Os that can be issued to a given database file will be limited.
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