Veritas Storage Foundation™ for Oracle 5.0.1 Administrator's Guide

Changes the default initial extent size. VxFS determines the
size of the first extent to be allocated to the file based on
the first write to a new file. Normally, the first extent is the
smallest power of 2 that is larger than the size of the first
write. If that power of 2 is less than 8K, the first extent
allocated is 8K. After the initial extent, the file system
increases the size of subsequent extents (see
max_seqio_extent_size) with each allocation. Since
most applications write to files using a buffer size of 8K or
less, the increasing extents start doubling from a small
initial extent. initial_extent_size can change the
default initial extent size to be larger, so the doubling policy
will start from a much larger initial size and the file system
will not allocate a set of small extents at the start of file.
Use this parameter only on file systems that will have a very
large average file size. On these file systems, it will result
in fewer extents per file and less fragmentation.
initial_extent_size is measured in file system blocks.
initial_extent_ size
The maximum buffer size allocated for file data; either 8K
bytes or 64K bytes. Use the larger value for workloads where
large reads/writes are performed sequentially. Use the
smaller value on workloads where the I/O is random or is
done in small chunks. The default value is 8K bytes.
max_buf_data_size
The maximum size of a direct I/O request that will be issued
by the file system. If a larger I/O request comes in, then it
is broken up into max_direct_iosz chunks. This
parameter defines how much memory an I/O request can
lock at once, so it should not be set to more than 20 percent
of memory.
max_direct_iosz
Limits the maximum disk queue generated by a single file.
When the file system is flushing data for a file and the
number of pages being flushed exceeds max_diskq,
processes will block until the amount of data being flushed
decreases. Although this doesn't limit the actual disk queue,
it prevents flushing processes from making the system
unresponsive. The default value is 1MB.
max_diskq
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