HP-UX Reference (11i v2 03/08) - 5 Miscellaneous Topics, 7 Device (Special) Files, 9 General Information, Index (vol 9)

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hfs_revra_per_disk(5) hfs_revra_per_disk(5)
(Tunable Kernel Parameters)
NAME
hfs_revra_per_disk - maximum HFS file system blocks to be read in one read-ahead operation when
sequentially reading backwards
VALUES
Failsafe
64
Default
64
Allowed values
0 to 8192
DESCRIPTION
This tunable defines the maximum number of file system blocks to be read in one read-ahead operation
when sequentially reading backwards.
Who Is Expected to Change This Tunable?
HP Field engineers, but not customers directly.
When Should the Value of This Tunable Be Raised?
The value of this tunable should be increased if there is a large number of reverse sequential file I/O on
file systems with small file system block size.
What Are the Side Effects of Raising the Value?
The system will consume more memory in the buffer cache.
When Should the Value of This Tunable Be Lowered?
The value of this tunable should be lowered when there is a smaller number of reverse sequential file I/O
on files systems with large file system block size.
What Are the Side Effects of Lowering the Value?
The file throughput rate will be decreased.
What Other Tunables Should Be Changed at the Same Time?
None.
WARNINGS
All HP-UX kernel tunable parameters are release specific. This parameter may be removed or have its
meaning changed in future releases of HP-UX.
AUTHOR
hfs_revra_per_disk was developed by HP.
HP-UX 11i Version 2: August 2003 − 1 − Hewlett-Packard Company Section 5−−111