swapon(2)swapon(2)NAMEswapon() - add swap space for interleaved paging and swapping
SYNOPSIS
Remarks
The ANSI C "" construct denotes a variable length argument list whose
optional and required members are given in the associated comment
DESCRIPTION
The system call makes a block device or a directory named path avail‐
able to the system for paging and swapping.
priority indicates the order in which the swap space from the device or
file system is used. It has a range of 0 (highest) to 10 (lowest).
Space is taken from the lower-numbered systems first.
can be used only by users who have appropriate privileges.
If path names a block device file
makes it available to the system at the specified priority for alloca‐
tion for paging and swapping.
In this form, takes only two arguments: the path to the block device
file, and the priority.
The device associated with path can be a device already known to the
system, defined at system configuration time, or it can be a previously
unspecified device.
If the device was already defined at system configuration time and also
has a start and/or size defined for that swap device, these values are
used.
Otherwise, if a filesystem exists on the device, swap is added follow‐
ing the filesystem, or if no filesystem exists, the complete device is
used for swap.
See the appropriate system administrator's manual for information on
how the size of the swap area is calculated.
If path names a directory
makes the blocks on the file system rooted at path available for paging
and swapping.
The min, limit, and reserve arguments are passed and used only if the
path argument names a directory.
min indicates the number of file system blocks to take from the file
system when is called.
limit indicates the maximum number of file system blocks the swap sys‐
tem is allowed to take from the file system.
reserve indicates the number of file system blocks that are saved for
file system use only.
For a pre-existing directory swap, a value of -1 for min, limit,
reserve, or priority will keep the value unchanged. This can be used
to change selective values without affecting others. For example, if
priority of a pre-existing directory swap needs to be changed without
affecting the values of min, limit, or reserve, one can specify the new
priority value and pass -1 for other arguments.
The size for the file system blocks mentioned above is the preferred
file system block size. The preferred file system block size can be
obtained by the call. The value of min, limit, or reserve is rounded
up to the tunable size.
ERRORS
If fails, is set to one of the following values.
A component of the path prefix denies search permission.
One of priority, min, limit, or reserve arguments is
invalid.
The device associated with
path already has swap turned on.
The device associated with
path is already in use.
The device associated with
path was specified at system configuration time
to add swap at a specified location, but that
location is within an existing file system on the
device.
The LIF header on the device associated with
path contains inconsistent directory data.
Unable to read the device associated with
path.
Too many symbolic links were encountered in translating the path
name.
The length of the specified path name exceeds
bytes, or the length of a component of the path
name exceeds bytes while is in effect.
The device associated with
path does not exist.
The system-imposed limit on the number of swap file entries has
been reached.
There is is not enough available space
on the specified file system or device.
The device associated with
path was specified at system configuration time
to add swap following the file system, but no
file system was found.
The path argument is not a block special file or the
root directory of a file system.
A component of the path is not a directory.
The device associated with
path could not be opened.
The effective user ID is not a user with appropriate privileges.
The device associated with
path is read-only.
WARNINGS
On systems running VxVM 3.5, the swap volumes to be configured for sys‐
tem crash dumps should be created with the usage type as during the
creation of the swap volume. Not doing so will cause a dump corrup‐
tion. You could use the option of to do the same.
No means is available to stop swapping to a device.
The system allocates no less than the amount specified in min. How‐
ever, to make the most efficient use of space, more than the amount
requested might be taken from the file system. The actual amount taken
will not exceed the number of file system blocks indicated in reserve.
Swapping to a file system is usually slower than swapping to a device.
Once file system blocks have been allocated for swap space, the file
system can not be unmounted unless the system is rebooted.
is the replacement for is to be obsoleted at a future date.
AUTHOR
was developed by the University of California, Berkeley.
SEE ALSOswapon(1M), vxassist(1M), swapctl(2), privileges(5).
TO BE OBSOLETED swapon(2)