Veritas File System 5.0 Administrator's Guide (September 2006)
option, the mount command prints the following error message and terminates
without mounting the file system.
VxFDD: You don't have a license to run this program
vxfs mount: Quick I/O not available
To enable or disable Quick I/O
1
Specify the -o qio mount option to enable Quick I/O:
# mount -F vxfs -o qio MyFS
2
Specify the -o noqio mount option to disable Quick I/O:
# mount -F vxfs -o noqio MyFS
Cached Quick I/O for databases
32-bit applications (such as 32-bit databases) can use a maximum of only 4 GB of
memory because of the 32-bit address limitation. The Cached Quick I/O feature
improves database performance on machines with sufficient memory by also
using the file system cache to store data.
For read operations through the Quick I/O interface, data is cached in the system
buffer cache, so subsequent reads of the same data can access this cached copy
and avoid doing disk I/O. To maintain the correct data in its buffer for write
operations, Cached Quick I/O keeps the buffer cache in sync with the data written
to disk.
With 64-bit applications, for which limited memory is not a critical problem, using
the file system cache still provides performance benefits by using the read-ahead
functionality. Because of the read-ahead functionality, sequential table scans will
benefit the most from using Cached Quick I/O by significantly reducing the query
response time.
Enabling Cached Quick I/O
Caching for Quick I/O files can be enabled online when the database is running.
See the vxtunefs(1M) and qioadmin(1) manual pages.
Note: Quick I/O must be enabled on the file system for Cached Quick I/O to operate.
Quick I/O for Databases
Cached Quick I/O for databases
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