How much swap space can I add to rp

[frederick hannah]

I have an 11.11(v1) machine with 16 GB of physical memory, and 8GB of primary swap. I am being asked to increase swap 2 to 3 times the memory amount. Kernal parm maxswapchunks is 16384. What is the max amount of swap I can add to my server?

[Michael Steele_2]

Do it. No problem.

http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=228218&admit=109447626+1245179146761+28353475

[frederick hannah]

Are you saying I can increase secondary swap to 32GB without re-tuning the maxswapchunk or any other kernel parm?

[sujit kumar singh]

hi

can you check if there is another kernel parameter called swchunk?

maximjum allowable swap space = maxswapchunks*swchunk

i do not remember exactly of swchunk is there in the 11.11 kernel
regards
sujit

[frederick hannah]

Yes, there is an swchunk kernel parm in 11.11. My server setting for this parm is 2048. So i am looking at 16384*2048 as the max amount of swap space allowed on my server?

[sujit kumar singh · Accepted solution]

Hi

swchunk is expressed in KB pages.
So maximum your system with the current swchunk set at 2048 can go up to 16384*2048/1024 MB of RAM that is 32 GB.

swchunk can also be increased if required.



http://docs.hp.com/en/B2355-60105/swchunk.5.html

regards
sujit

[sujit kumar singh]

Hi frederik,


please assign points to the replies made to your questions. This helps you get better responses.

regards
sujit

[frederick hannah]

thanks. You guys have been a great help

[Bill Hassell]

Actually, for your version (11.11), swchunk should be left alone. The correct parameter is maxswapchunks. After 11.11, maxswapchunks is no longer used. The size of swchunk changes the way that the kernel manages swap space so it is recommended to leave it static. The formula is:

maxswapchunks * swchunk * dev_bsize

where: swchunk=2048 and dev_bsize=1024

which simplifies to desired_swap_size_MB/2. So maxswapchunks for 3*16 GB total swap (48 GB) would be 24000. Your current value (16384) will allow a total of 32 GB of swap space.