nswapfs(5) nswapfs(5)
Tunable Kernel Parameters
NAME [Toc] [Back]
nswapfs - maximum number of file systems that can be enabled for swap
VALUES [Toc] [Back]
Default
10 file systems
Allowed values [Toc] [Back]
Minimum: 0 file systems
Maximum: 25 files systems
DESCRIPTION [Toc] [Back]
File system swap devices are managed in a table for easier indexing in
the kernel. nswapfs sets the kernel variable responsible for the
upper limit on this table, and thus the upper limit to file systems
which can be used for swap.
Who is Expected to Change This Tunable?
Anyone.
Restrictions on Changing [Toc] [Back]
Changes to this tunable take effect at the next reboot.
When Should the Value of This Tunable Be Raised?
If another file system swap is added to the system which would
increase the number above nswapfs, then swapon() returns [ENOENT] to
the caller (see the swapon(2) manpage).
What Are the Side Effects of Raising the Value?
More file systems for swap can be added to the system, and the kernel
will need a little more memory for the table. A small performance
side effect of the kernel having to scan more file systems to check
for a duplicate during swapon is also true, but realistically
negligible.
When Should the Value of This Tunable Be Lowered?
Only if you are sure the system will never go over a certain number of
swap file systems, and you wish to lower this tunable to save a small
amount of kernel memory and kernel performance during swapon
operations.
What Are the Side Effects of Lowering the Value?
No side effects other than the primary and presumably desired new
limitation on the number of swap file systems.
What Other Tunable Values Should Be Changed at the Same Time?
None.
WARNINGS [Toc] [Back]
All HP-UX kernel tunable parameters are release specific. This
Hewlett-Packard Company - 1 - HP-UX 11i Version 2: Sep 2004
nswapfs(5) nswapfs(5)
Tunable Kernel Parameters
parameter may be removed or have its meaning changed in future
releases of HP-UX.
Installation of optional kernel software, from HP or other vendors,
may cause changes to tunable parameter values. After installation,
some tunable parameters may no longer be at the default or recommended
values. For information about the effects of installation on tunable
values, consult the documentation for the kernel software being
installed. For information about optional kernel software that was
factory installed on your system, see HP-UX Release Notes at
http://docs.hp.com.
AUTHOR [Toc] [Back]
nswapfs was developed by HP.
Hewlett-Packard Company - 2 - HP-UX 11i Version 2: Sep 2004 [ Back ] |
