Large swap space - adjust kernel?

[dictum9]

On this rx4640, I have 24GB of memory and chose twice that for swap, or 48GB.
During the system install, I am getting the following. Does it mean some kernel parameter needs to be adjusted once the system is up?



NOTE: Unable to set kernel tunable to account for all the swap space on the
system. There will be some swap space which will not be usable on the
final system and messages may appear on initial startup. In order to
use all the swap space the kernel

[Marvin Strong · Accepted solution]

Depending on your OS version try to increase maxswapchunks kernel parameter

[Deoncia Grayson_1]

I would be curious to know the current value for maxswapchunks, you can read this document for further understanding of this parameter.

http://docs.hp.com/en/TKP-90202/re38.html

[dictum9]

I cannot find any reference to maxswapchunks
in the /stand/system file. Or via sam.

[Jeff_Traigle]

maxswapchunks is not a tunable parameter in 11.23. You are still able to tune swchunk, however.

[inventsekar_1]

/etc,

"On this rx4640, I have 24GB of memory"
the 24 GB is the harddisk only. isnt?
or RAM size?

and is pseudo swap enabled?
check it with:
#kmtune -q swapmem_on --11iv1
#kctune swapmem_on --11iv2

rx4640 Hardware Specifications:
Supports up to eight Double Data Rate (DDR) registered ECC Memory, in PC1600
DIMMs. Supported DDR DIMM sizes: 128MB, 256MB, 513MB, 1GB, 2GB, and
4GB. Requires DIMMs to be added in quads of equal capacity.
http://docs.hp.com/en/rx4640_ops/rx4640_ops.pdf

[inventsekar_1]

this is from SNA I training student guides:

these kernel parameters limit the amount of swap:
1. maxswapchunks controls the maximum amount of swap space. default value:256. each chunk of swap space is 2MB. the size of swapchunk can be modified with the "swchunk".

in 11iv2 machine:
# kctune -v swchunk
Tunable swchunk
Description Swap chunk size (kBytes)
Module vm
Current Value 2048 [Default]
Value at Next Boot 2048 [Default]
Value at Last Boot 2048
Default Value 2048
Constraints swchunk >= 2048
swchunk <= 65536
Can Change At Next Boot Only

2. nswapdev in /stand/system sets the maximum number of dynamically configured swap devices at ten(default). the maximum is 25. more than nswapdev swap devices require a kernel regeneration.

3. nswapfs, determines the maximum number of file systems you can enable for swap. the default is 10 and maximum is 25.