swap(1m) - osol9

1swap(1M)                System Administration Commands                swap(1M)
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NAME

6       swap - swap administrative interface
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SYNOPSIS

9       /usr/sbin/swap -a swapname [swaplow] [swaplen]
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12       /usr/sbin/swap -d swapname [swaplow]
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15       /usr/sbin/swap -l [-h | -k]
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18       /usr/sbin/swap -s [-h]
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DESCRIPTION

22       The  swap utility provides a method of adding, deleting, and monitoring
23       the system swap areas used by the memory manager.
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OPTIONS

26       The following options are supported:
27
28       -a swapname [swaplow] [swaplen]
29
30           Add the specified swap area. This option can only be  used  by  the
31           superuser or by one who has assumed the Primary Administrator role.
32           swapname is the name of the swap area or regular file. For example,
33           on  system running a UFS root file system, specify a slice, such as
34           /dev/dsk/c0t0d0s1, or a regular file for a swap area. On  a  system
35           running   a  ZFS  file  system,  specify  a  ZFS  volume,  such  as
36           /dev/zvol/dsk/rpool/swap, for a swap area. Using a regular file for
37           swap is not supported on a ZFS file system. In addition, you cannot
38           use the same ZFS volume for both the swap area and  a  dump  device
39           when the system is running a ZFS root file system.
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41           swaplow  is  the  offset in 512-byte blocks into the file where the
42           swap area should begin. swaplen is the desired length of  the  swap
43           area  in 512-byte blocks. The value of swaplen can not be less than
44           16. For example, if n blocks are specified, then (n-1) blocks would
45           be  the  actual  swap  length. swaplen must be at least one page in
46           length. The size of a page of memory can be determined by using the
47           pagesize  command.  See pagesize(1). Since the first page of a swap
48           file is automatically skipped, and a swap file needs to be at least
49           one  page  in  length,  the  minimum size should be a multiple of 2
50           pagesize bytes. The size of a page of memory is machine-dependent.
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52           swaplow + swaplen must be less than or equal to  the  size  of  the
53           swap  file.  If  swaplen  is  not  specified, an area will be added
54           starting at swaplow and extending to  the  end  of  the  designated
55           file.  If neither swaplow nor swaplen are specified, the whole file
56           will be used except for the first page.  Swap  areas  are  normally
57           added  automatically  during  system  startup  by the /sbin/swapadd
58           script. This script adds all swap areas which have  been  specified
59           in  the  /etc/vfstab  file; for the syntax of these specifications,
60           see vfstab(4).
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62           To use an NFS or local file system swapname, you should first  cre‐
63           ate  a file using mkfile(1M). A local file system swap file can now
64           be added to the running system by just running the swap -a command.
65           For NFS mounted swap files, the server needs to export the file. Do
66           this by performing the following steps:
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68               1.     Add the following line to /etc/dfs/dfstab:
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70                        share -F nfs -o \
71                        rw=clientname,root=clientname path-to-swap-file
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74               2.     Run shareall(1M).
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76               3.     Have the client add the following line to /etc/vfstab:
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78                        server:path-to-swap-file -  local-path-to-swap-file nfs \
79                             --- local-path-to-swap-file -- swap ---
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81
82               4.     Have the client run mount:
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84                        # mount local-path-to-swap-file
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88               5.     The client can then run swap -a to add the swap space:
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90                        # swap -a local-path-to-swap-file
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94
95       -d swapname
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97           Delete the specified swap area. This option can only be used by the
98           super-user.  swapname  is  the  name of the swap file: for example,
99           /dev/dsk/c0t0d0s1 or a regular  file.  swaplow  is  the  offset  in
100           512-byte blocks into the swap area to be deleted. If swaplow is not
101           specified, the area will be deleted starting at  the  second  page.
102           When  the command completes, swap blocks can no longer be allocated
103           from this area and all swap blocks previously in use in  this  swap
104           area have been moved to other swap areas.
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106
107       -h
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109           All sizes are scaled to a human readable format. Scaling is done by
110           repetitively dividing by 1024.
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112
113       -k
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115           Write the files sizes in units of 1024 bytes.
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117
118       -l
119
120           List the status of all the swap areas. The output has five columns:
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122           path
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124               The path name for the swap area.
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127           dev
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129               The major/minor device number in decimal if it is a block  spe‐
130               cial device; zeroes otherwise.
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133           swaplo
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135               The swaplow value for the area in 512-byte blocks.
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138           blocks
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140               The swaplen value for the area in 512-byte blocks.
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142
143           free
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145               The  number  of  512-byte blocks in this area that are not cur‐
146               rently allocated.
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148           The list does not include swap space in the form of physical memory
149           because this space is not associated with a particular swap area.
150
151           If swap -l is run while swapname is in the process of being deleted
152           (by swap-d), the string INDEL will appear in a sixth column of  the
153           swap stats.
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155
156       -s
157
158           Print  summary  information about total swap space usage and avail‐
159           ability:
160
161           allocated
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163               The total amount of swap space in bytes currently allocated for
164               use as backing store.
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166
167           reserved
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169               The  total  amount  of  swap space in bytes not currently allo‐
170               cated, but claimed by memory mappings for possible future use.
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172
173           used
174
175               The total amount of swap space in bytes that  is  either  allo‐
176               cated or reserved.
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178
179           available
180
181               The  total  swap space in bytes that is currently available for
182               future reservation and allocation.
183
184           These numbers include swap space from all configured swap areas  as
185           listed by the -l option, as well swap space in the form of physical
186           memory.
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188

USAGE

190       On the 32-bit operating system, only the first 2 Gbytes -1 are used for
191       swap  devices  greater than or equal to 2 Gbytes in size. On the 64-bit
192       operating system, a block device larger than 2 Gbytes can be fully uti‐
193       lized for swap up to 2^63 −1 bytes.
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ENVIRONMENT VARIABLES

196       See  environ(5) for descriptions of the following environment variables
197       that affect the execution of swap: LC_CTYPE and LC_MESSAGE.
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ATTRIBUTES

200       See attributes(5) for descriptions of the following attributes:
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205       ┌─────────────────────────────┬─────────────────────────────┐
206       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
207       ├─────────────────────────────┼─────────────────────────────┤
208       │Availability                 │SUNWcsu                      │
209       └─────────────────────────────┴─────────────────────────────┘
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NOTES

216       For  information  about  setting  up  a swap area with ZFS, see the ZFS
217       Administration Guide.
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WARNINGS

220       No check is done to determine if a swap area being added overlaps  with
221       an existing file system.
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225SunOS 5.11                        11 Apr 2008                         swap(1M)