Veritas File System 5.0 Administrator's Guide (September 2006)

Table 2-1
Tunable VxFS I/O parameters (continued)
DescriptionParameter
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
Specifies the minimum size to qualify a deleted inode for
inode aging. Inode aging is used in conjunction with file
system Storage Checkpoints to allow quick restoration of
large, recently deleted files. For best performance, it is
advisable to age only a limited number of larger files
before completion of the removal process. Setting the size
too low can push larger file inodes out of the aging queue
to make room for newly removed smaller file inodes.
inode_aging_size
The maximum size of a direct I/O request that are 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 buffers being flushed exceeds max_diskq,
processes are blocked until the amount of data being
flushed decreases. Although this does not limit the actual
disk queue, it prevents flushing processes from making
the system unresponsive. The default value is 1 MB.
max_diskq
51VxFS performance: creating, mounting, and tuning file systems
Tuning I/O