JFS2 size limits

PV Distribution

-Edge, middle, center, inner-middle, inner-edge. These are the different regions where a logical volume can live. Using different distributions will give you different types of performance. 

Example:

-Put things that need fast, sequential access on the edge.  This moves the disk media under the read head at a faster rate.  Though, the outer edge is slow at random access because of the distance the read head must move.

-Put things that need fast, random access on the inner edge, the read head needs to move less to find data on this area.

Paging Space

Before creating the additional paging:

# lsps -a
Page Space      Physical Volume   Volume Group    Size %Used Active  Auto  Type Chksum
paging00        hdisk7            rootvg        8832MB     1   yes   yes    lv     0
hd6             hdisk7            rootvg         512MB     1   yes   yes    lv     0
#

Create LV for Paging:

#mklv -y paging01 -t paging rootvg 128 hdisk14
paging01

Add to paging:

# swapon /dev/paging01

#lsps -s
Total Paging Space   Percent Used
      17536MB               1%

# lsps -a
Page Space      Physical Volume   Volume Group    Size %Used Active  Auto  Type Chksum
paging01        hdisk7            rootvg        8192MB     1   yes    no    lv     0
paging00        hdisk7            rootvg        8832MB     1   yes   yes    lv     0
hd6             hdisk7            rootvg         512MB     1   yes   yes    lv     0
#


What is paging space?

–Virtual Memory

–Memory and paging space both composed of“pages”

-Memory and paging space are divided into four kilobyte chunks called pages (or page frames).  There should always be at least one page of paging space for each page of physical memory.

-Data in memory that is not being used can be “paged out” to paging space to make room for other data

-Access to paging space is, since it is on a disk, slow in comparison to memory access

To view the paging spaces on a node:

#ls -a
Page Space  Physical Volume   Volume Group    Size   %Used  Active  Auto  Type
paging01    hdisk2            db2wh01vg     1024MB      10     yes   yes    lv
hd6         hdisk0            rootvg         512MB      20     yes   yes    lv

Removing a paging space:

Set to not activate on reboot

chps –a n .

Reboot

shutdown -Fr

Remove paging space:

rmps

(OR)

with AIX version 5.1 and above, paging spaces can be removed on-the-fly. 

Starting with AIX 5.1, paging space can be added and removed on the fly.  
To deactive a paging space immediately in AIX 5.1+, use the swapoff command.  
This will move any data stored in that paging space to other paging spaces and immediately deactivate the paging space.  
If there is not enough room in other paging spaces to hold the contents of the paging space being swapped off, the command will fail.

Types of Volume Groups and Limitaion

Volume Groups have 3 different types:

VG type       Max PVs    Max LVs      Max PPs per VG          Maximum PP size

Normal VG       32            256          32,512 (1016 * 32)        1 GB
Big VG            128           512          130,048 (1016 * 128)    1 GB
Scalable VG    1024          4096         2,097,152                    128 GB

Note: Scalable VG AIX 5.3 and above, PV and LV limitations can be defined by the administrator.

LED Codes and Error status

LED Codes: