InfoScale™ 9.0 Storage and Availability Management for DB2 Databases - AIX, Linux
- Section I. Storage Foundation High Availability (SFHA) management solutions for DB2 databases
- Overview of Storage Foundation for Databases
- About Veritas File System
- Overview of Storage Foundation for Databases
- Section II. Deploying DB2 with InfoScale products
- Deployment options for DB2 in a Storage Foundation environment
- Deploying DB2 with Storage Foundation
- Deploying DB2 in an off-host configuration with Storage Foundation
- Deploying DB2 with High Availability
- Deployment options for DB2 in a Storage Foundation environment
- Section III. Configuring Storage Foundation for Database (SFDB) tools
- Configuring and managing the Storage Foundation for Databases repository database
- Configuring the Storage Foundation for Databases (SFDB) tools repository
- Configuring authentication for Storage Foundation for Databases (SFDB) tools
- Configuring and managing the Storage Foundation for Databases repository database
- Section IV. Improving DB2 database performance
- About database accelerators
- Improving database performance with Quick I/O
- About Quick I/O
- Improving DB2 database performance with Veritas Concurrent I/O
- Section V. Using point-in-time copies
- Understanding point-in-time copy methods
- Volume-level snapshots
- Storage Checkpoints
- Considerations for DB2 point-in-time copies
- Administering third-mirror break-off snapshots
- Administering Storage Checkpoints
- Database Storage Checkpoints for recovery
- Backing up and restoring with Netbackup in an SFHA environment
- Understanding point-in-time copy methods
- Section VI. Optimizing storage costs for DB2
- Section VII. Storage Foundation for Databases administrative reference
- Storage Foundation for Databases command reference
- Tuning for Storage Foundation for Databases
- Troubleshooting SFDB tools
Table scans
Quick I/O in its default mode performs all I/O as direct I/O.
In the case of single-threaded sequential scans (common in decision support system (DSS) workloads), using buffered reads can yield better performance. Because the file system detects these sequential reads and performs read-aheads, the next few blocks that are requested by DB2 are readily available in the system buffer cache and are simply copied to the DB2 buffer pool. Because access from memory is inherently faster than access from disk, this achieves a significant reduction in response time.
To handle large sequential scans when using Quick I/O, two methods are available to improve performance:
Modify the DB2 PREFETCH setting to force reading in data before it is required.
The second method is to enable Cached Quick I/O for the files that would be read by the DB2 sequential scan process. Cached Quick I/O enables buffered reads, and the automatic file system read-ahead helps lower response times by pre-loading data. A major advantage of using Cached Quick I/O is that it does not require any database level changes and so does not require the database to be restarted for changes to take effect.