Veritas™ File System 5.0.1 Administrator's Guide

Table 2-1
Tunable VxFS I/O parameters (continued)
DescriptionParameter
Changes the default initial extent size. VxFS determines,
based on the first write to a new file, the size of the first
extent to be allocated to the 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 with each
allocation.
See max_seqio_extent_size.
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 starts from a much larger initial size and the file
system does not allocate a set of small extents at the start
of file. Use this parameter only on file systems that have
a very large average file size. On these file systems it
results in fewer extents per file and less fragmentation.
initial_extent_size is measured in file system
blocks.
initial_extent_size
Specifies the maximum number of inodes to place on an
inode aging list. Inode aging is used in conjunction with
file system Storage Checkpoints to allow quick restoration
of large, recently deleted files. The aging list is maintained
in first-in-first-out (fifo) order up to maximum number
of inodes specified by inode_aging_count. As newer
inodes are placed on the list, older inodes are removed to
complete their aging process. For best performance, it is
advisable to age only a limited number of larger files
before completion of the removal process. The default
maximum number of inodes to age is 2048.
inode_aging_count
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. 8K bytes is the default value.
max_buf_data_size
VxFS performance: creating, mounting, and tuning file systems
Tuning I/O
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