Veritas InfoScale™ 7.4 Solutions Guide - Solaris
- Section I. Introducing Veritas InfoScale
- Section II. Solutions for Veritas InfoScale products
- Section III. Improving database performance
- Overview of database accelerators
- Improving database performance with Veritas Quick I/O
- About Quick I/O
- Improving database performance with Veritas Cached Quick I/O
- Improving database performance with Veritas Concurrent I/O
- Section IV. Using point-in-time copies
- Understanding point-in-time copy methods
- Backing up and recovering
- Preserving multiple point-in-time copies
- Online database backups
- Backing up on an off-host cluster file system
- Database recovery using Storage Checkpoints
- Backing up and recovering in a NetBackup environment
- Off-host processing
- Creating and refreshing test environments
- Creating point-in-time copies of files
- Section V. Maximizing storage utilization
- Optimizing storage tiering with SmartTier
- Optimizing storage with Flexible Storage Sharing
- Optimizing storage tiering with SmartTier
- Section VI. Migrating data
- Understanding data migration
- Offline migration from Solaris Volume Manager to Veritas Volume Manager
- How Solaris Volume Manager objects are mapped to VxVM objects
- Overview of the conversion process
- Planning the conversion
- Preparing a Solaris Volume Manager configuration for conversion
- Setting up a Solaris Volume Manager configuration for conversion
- Converting from the Solaris Volume Manager software to VxVM
- Post conversion tasks
- Online migration of a native file system to the VxFS file system
- Migrating a source file system to the VxFS file system over NFS v3
- VxFS features not available during online migration
- Migrating storage arrays
- Migrating data between platforms
- Overview of the Cross-Platform Data Sharing (CDS) feature
- CDS disk format and disk groups
- Setting up your system to use Cross-platform Data Sharing (CDS)
- Maintaining your system
- Disk tasks
- Disk group tasks
- Displaying information
- File system considerations
- Specifying the migration target
- Using the fscdsadm command
- Maintaining the list of target operating systems
- Migrating a file system on an ongoing basis
- Converting the byte order of a file system
- Migrating from Oracle ASM to Veritas File System
- Section VII. Veritas InfoScale 4K sector device support solution
How Cached Quick I/O works in a Sybase environment
Cached Quick I/O is a specialized external caching mechanism specifically suitable to 32-bit ports of the Sybase server. Cached Quick I/O can be used on 64-bit ports of the Sybase server, but the benefits are not as great. Cached Quick I/O can be selectively applied to datafiles that are suffering an undesirable amount of physical disk I/O due to insufficient dataserver buffer caches. Cached Quick I/O works by taking advantage of the available physical memory that is left over after the operating system reserves the amount it needs and the Sybase dataserver buffer cache has been sized to the maximum capacity allowed within a 32-bit virtual address space. This extra memory serves as a cache to store file data, effectively serving as a second-level cache backing the dataserver buffer caches.
For example, consider a system configured with 12GB of physical memory, an operating system using 1GB, and a total Sybase size of 3.5GB. Unless you have other applications running on your system, the remaining 7.5GB of memory is unused. If you enable Cached Quick I/O, these remaining 7.5GB become available for caching database files.
Note:
You cannot allocate specific amounts of the available memory to Cached Quick I/O. When enabled, Cached Quick I/O takes advantage of available memory.
Cached Quick I/O is not beneficial for all device files in a database. Turning on caching for all database device files can degrade performance due to extra memory management overhead (double buffer copying). You must use file I/O statistics to determine which individual database device files benefit from caching, and then enable or disable Cached Quick I/O for individual device files.
If you understand the applications that generate load on your database and how this load changes at different times during the day, you can use Cached Quick I/O to maximize performance. By enabling or disabling Cached Quick I/O on a per-file basis at different times during the day, you are using Cached Quick I/O to dynamically tune the performance of a database.
For example, files that store historical data are not generally used during normal business hours in a transaction processing environment. Reports that make use of this historical data are generally run during off-peak hours when interactive database use is at a minimum. During normal business hours, you can disable Cached Quick I/O for database files that store historical data in order to maximize memory available to other user applications. Then, during off-peak hours, you can enable Cached Quick I/O on the same files when they are used for report generation. This will provide extra memory resources to the database server without changing any database configuration parameters. Enabling file system read-ahead in this manner and buffering read data can provide great performance benefits, especially in large sequential scans.
You can automate the enabling and disabling of Cached Quick I/O on a per-file basis using scripts, allowing the same job that produces reports to tune the file system behavior and make the best use of system resources. You can specify different sets of files for different jobs to maximize file system and database performance.