swapinfo.1m (2010 09)
s
swapinfo(1M) swapinfo(1M)
When a process is created, or requests additional space, space is reserved for it by increasing the space
shown on the reserve line above. When paging activity actually occurs, space is used in one of the
paging areas (the one with the lowest priority number that has free space available, already allocated),
and that space will be shown as used in that area.
The sum of the space used in all of the paging areas, plus the amount of space reserved, can never exceed
the total amount allocated in all of the paging areas. If a request for more memory occurs which would
cause this to happen, the system tries several options:
1. The system tries to increase the total space available by allocating more space in file system paging
areas.
2. If all file system paging areas are completely allocated and the request is still not satisfied, the sys-
tem will try to use memory paging as described on the
memory line above. (Memory paging is con-
trolled by the tunable parameter
swapmem_on, which defaults to 1 (on). If this parameter is
turned off, the memory line will not appear.)
3. If memory paging also cannot satisfy the request, because it is full or turned off, the request is
denied.
Several implications of this procedure are noteworthy for understanding the output of
swapinfo:
• Paging space will not be allocated in a file system paging area (except for the minimum specified
when the area is first enabled) until all device paging space has been reserved, even if the file sys-
tem paging area has a lower priority value.
• When paging space is allocated to a file system paging area, that space becomes unavailable for user
files, even if there is no paging activity to it.
• Requests for more paging space will fail when they cannot be satisfied by reserving device, file sys-
tem, or memory paging, even if some of the reserved paging space is not yet in use. Thus it is possi-
ble for requests for more paging space to be denied when some, or even all, of the paging areas show
zero usage — space in those areas is completely reserved.
• System available memory is shared between the paging subsystem and kernel memory allocators.
Thus, the system may show memory paging usage before all available disk paging space is com-
pletely reserved or fully allocated.
Logical Volume Manager (LVM)
The
swapinfo command displays swap logical volume if the system was installed with LVM. To modify
swap logical volume, refer to the LVM commands and manpages for lvlnboot and lvrmboot.For
example, to remove a swap logical volume, run the following LVM command:
lvrmboot -s
Options
swapinfo recognizes the following options:
-s In addition to printing information about device and file system paging space that are
currently in use, swapinfo will also print information about primary paging area configured
for next boot using swapon(1M).
If the primary paging area for next boot has not been configured using swapon (1M),
swapinfo -s will not be able to display any information. In this case swapinfo -s will
display the error message - "Primary swap for next boot was not set using swapctl()"
-m Display the AVAIL, USED, FREE, START, LIMIT, and RESERVE values in Mbytes instead of
Kbytes, rounding off to the nearest whole Mbyte (multiples of 1024
2
). The output header for-
mat changes from Kb to Mb accordingly.
-t Add a totals line with a TYPE of total. This line totals only the paging information
displayed above it, not all paging areas; this line might be misleading if a subset of -dfrM is
specified.
-a Show all device paging areas, including those configured into the kernel but currently dis-
abled. (These are normally omitted.) The word disabled appears after the NAME, and the
Kb AVAIL, Kb USED, and Kb FREE values are 0. The -a option is ignored unless the -d
option is present or is true by default.
HP-UX 11i Version 3: September 2010 − 3 − Hewlett-Packard Company 3