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28 .\" @(#)swapon.8 8.1 (Berkeley) 6/5/93
35 .Nm swapon , swapoff , swapctl
36 .Nd "specify devices for paging and swapping"
58 utilities are used to control swap devices in the system.
59 At boot time all swap entries in
61 are added automatically when the system goes multi-user.
62 Swap devices use a fixed interleave; the maximum number of devices
64 There is no priority mechanism.
68 utility adds the specified swap devices to the system.
71 option is used, all swap devices in
73 will be added, unless their
83 option will be added as well as ones with no option.
87 informational messages will not be
88 written to standard output when a swap device is added.
91 option causes each of following devices to receive a
94 This command marks the device's blocks as unused, except those that
95 might store a disk label.
96 This marking can erase a crash dump.
99 for a device until after
101 has copied the crash dump to another location, use the
107 utility removes the specified swap devices from the system.
110 option is used, all swap devices in
112 will be removed, unless their
118 only swap devices with the
120 option will be removed.
124 informational messages will not be
125 written to standard output when a swap device is removed.
128 will fail and refuse to remove a swap device if a very conservative
129 check does not conclude that there is sufficient VM (memory +
130 remaining swap devices) to run the system.
133 option turns off this check, which could deadlock the system
134 if there is insufficient swap space remaining.
139 must move swapped pages out of the device being removed which could
140 lead to high system loads for a period of time, depending on how
141 much data has been swapped out to that device.
143 Other options supported by both
148 .Bl -tag -width indent
152 file to use (in conjunction with
158 utility exists primarily for those familiar with other
161 used to add, remove, or list swap devices.
164 option is used differently in
166 and indicates that a specific list of devices should be added.
169 option indicates that a specific list should be removed.
176 operate on all swap entries in
178 which do not have their
182 Swap information can be generated using the
192 utility has the following options for listing swap:
193 .Bl -tag -width indent
195 Output values in human-readable form.
197 Output values in gigabytes.
199 Output values in kilobytes.
201 Output values in megabytes.
203 List the devices making up system swap.
205 Print a summary line for system swap.
209 environment variable is used if not specifically
211 512 byte blocks are used by default.
214 .Bl -tag -width ".Pa /dev/{ada,da}?s?b" -compact
215 .It Pa /dev/{ada,da}?s?b
216 standard paging devices
221 file system description table
224 These utilities may fail for the reasons described in
242 utilities appeared in