*Sizing paging space
- hd6 is created at installation time: The recommended paging space formula is long standing, but it will likely result in having more space than is needed. Total paging space = 512M + ( memory size - 256M ) * 1.25
- However, the amount needed is dependent on applications and system usage.
- Paging space should be continually monitored, using:
# lsps -a
Page Space Physical Volume Volume Group Size %Used Active Auto Type Chksum
hd6 hdisk0 rootvg 21504MB 1 yes yes lv 0
# lsps -s
Total Paging Space Percent Used
21504MB 1%
# svmon
size inuse free pin virtual mmode
memory 4034560 3559958 474602 315690 2262424 Ded
pg space 5505024 8355
work pers clnt other
pin 192858 0 0 122832
in use 2262424 0 1297534
PageSize PoolSize inuse pgsp pin virtual
s 4 KB - 1922230 8355 168730 624696
m 64 KB - 102358 0 9185 102358
- Running low on paging space is bad. New processes will not start and the system may start killing processes.
- Paging space can be dynamically increased or decreased in size.
*Paging space placement
- Paging spaces roughly the same size
- Only one paging space per physical disk
- Use disks with the least activity
- Do not extend "a paging space" over multiple physical volumes
- Place on SAN disks for better performance
*Adding paging space
mkps [-a] [-n] [-t Type] -s NumLPs Vgname [Pvname]
-s NumLPs : Sets the size of the new paging space in logical partitions
-a : Activate the paging space at the next restart (adds it to /etc/swapspaces)
-n : Activate the paging space immediately.
-t Type : Specifies the type of paging space (lv or nfs)
# mkps -s 10 -n -a rootvg hdisk1 (or)
# smitty mkps
Add Another Paging Space
Type or select values in entry fields.
Press Enter AFTER making all desired changes.
[Entry Fields]
Volume group name rootvg
SIZE of paging space (in logical partitions) [10] #
PHYSICAL VOLUME name hdisk1 +
Start using this paging space NOW? yes +
Use this paging space each time the system is yes +
RESTARTED?
Checksum Size [] +#
*Change paging space
-- Delete one logical partition from the paging00 paging space:
# chps -d 1 paging00
-- Add one logical partition to the paging00 paging space:
# chps -s 1 paging00
(or)
# smitty chps
Change / Show Characteristics of a Paging Space
Type or select values in entry fields.
Press Enter AFTER making all desired changes.
[Entry Fields]
Paging space name paging00
Volume group name rootvg
Physical volume name hdisk1
NUMBER of additional logical partitions [] #
Or NUMBER of logical partitions to remove [5] #
Use this paging space each time the system is yes +
RESTARTED?
Checksum Size [0] +#
*Removing paging space
(1) First, deactivate the paging space.
# swapoff /dev/paging00
(2) remove the paging space.
# rmps /dev/paging00
(or)
# smitty rmps
Remove a Paging Space
Type or select values in entry fields.
Press Enter AFTER making all desired changes.
[Entry Fields]
PAGING SPACE name paging00 +
*Problems with paging space
(1) Monitor the system carefully
-- If paging space is running low or gets to 100% full, the system will panic. Errors will be seen on the console, such as INIT: Paging space is low!
-- The kernel will randomly start to kill processes. UNIX version 7 manual, quote: "Absolute mayhem guaranteed"
(2) Paging space too small:
-- Dynamically increase the size by allocating more partitions.
OR
-- Add an additional paging space definition to another physical disk.
(3) Paging space too large:
-- Dynamically decrease the size by deallocating partitions.
OR
-- Remove a paging space definition.
*Documenting paging space setup
(1) Run the lsps command.
(2) Have a hardcopy of the /etc/swapspaces file.
# cat /etc/swapspaces
* /etc/swapspaces
*
* This file lists all the paging spaces that are automatically put into
* service on each system restart (the 'swapon -a' command executed from
* /etc/rc swaps on every device listed here).
*
* WARNING: Only paging space devices should be listed here.
*
* This file is modified by the chps, mkps and rmps commands and referenced
* by the lsps and swapon commands.
hd6:
dev = /dev/hd6
auto = yes
checksum_size = 0