Veritas™ File System 5.0.1 Administrator's Guide

Table 2-1
Tunable VxFS I/O parameters (continued)
DescriptionParameter
The default for all VxFS read operations is to perform
sequential read ahead. You can specify the read_ahead
cache advisory to implement the VxFS enhanced read
ahead functionality. This allows read aheads to detect
more elaborate patterns, such as increasing or decreasing
read offsets or multithreaded file accesses, in addition to
simple sequential reads. You can specify the following
values for read_ahead:
0—Disables read ahead functionality
1—Retains traditional sequential read ahead behavior
2—Enables enhanced read ahead for all reads
The default is 1—VxFS detects only sequential patterns.
read_ahead detects patterns on a per-thread basis, up
to a maximum determined by vx_era_nthreads
parameter. The default number of threads is 5, but you
can change the default value by setting the
vx_era_nthreads parameter in the /etc/system
configuration file.
read_ahead
59VxFS performance: creating, mounting, and tuning file systems
Tuning I/O