NAME
nswapdev — maximum number of devices that can be enabled for swap
VALUES
Allowed values
Minimum: 1 device
Maximum: 25 devices
DESCRIPTION
Swap devices are managed in a table for easier indexing in the
kernel.
nswapdev
sets the kernel variable responsible for the upper limit on this
table, and thus the upper limit to devices which can be used for swap.
Who is Expected to Change This Tunable?
Anyone.
Restrictions on Changing
Changes to this tunable take effect at the next reboot.
When Should the Value of This Tunable Be Raised?
If another swap device is added to the system which would increase
the number of devices above
nswapdev,
and
swapon()
returns
ENOENT
to the caller (see the
swapon(2)
manpage).
What Are the Side Effects of Raising the Value?
More devices 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 devices to check for a duplicate device 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 devices, 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 devices.
What Other Tunable Values 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
nswapdev
was developed by HP.
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