VERITAS Storage Foundation 4.1 Oracle Administrator's Guide

Tuning VxFS Prerelease 8 September 2005, 8:55am
408 VERITAS Storage Foundation for Oracle Administrator’s Guide
max_seqio_extent_
size
Increases or decreases the maximum size of an extent. When the file
system is following its default allocation policy for sequential writes to
a file, it allocates an initial extent that is large enough for the first write
to the file. When additional extents are allocated, they are
progressively larger (the algorithm tries to double the size of the file
with each new extent) so each extent can hold several writes’ worth of
data. This is done to reduce the total number of extents in anticipation
of continued sequential writes. When the file stops being written, any
unused space is freed for other files to use. Normally, this allocation
stops increasing the size of extents at 2048 blocks, which prevents one
file from holding too much unused space.
max_seqio_extent_size is measured in file system blocks.
qio_cache_enable Enables or disables caching on Quick I/O files. The default behavior is
to disable caching. To enable caching, set qio_cache_enable to 1.
On systems with large memories, the database cannot always use all of
the memory as a cache. By enabling file system caching as a second
level cache, performance may be improved. If the database is
performing sequential scans of tables, the scans may run faster by
enabling file system caching so the file system will perform aggressive
read-ahead on the files.