Swap Space

[pgorn]

I am going to add swap space to a system. I am adding another lvol$. What kernel params. do I need to check to see if they need to be changed or set. The box was not setup correctly and I want to make sure the kernel is setup so I can add swap space.
Thank you

[A. Clay Stephenson · Accepted solution]

The most important parameter is maxswapchunks which will probably need to be increased. It's okay to make it larger than the amount of swap you intend to have. Increasing this value will make adding additional swap possible w/o a reboot. The other value you should consider is swapmem_on. If you have swapspace >= RAM then there is no need to set this value to 1. You should probably also consider you values for max_dbc_pct, min_dbc_pct, (or bufpages if you are running a stitically sized buffer cache).

[James R. Ferguson]

Hi:

Look at 'maxswapchunks'.

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

Regards!

...JRF...

[pgorn]

swap space 4GB
PHY mem 25GB
I was going to add about 35GB of swap

[A. Clay Stephenson]

Okay, in that case we need to do a little more. The maximum value for maxswapchunks is 16384. With swchunk set at 2K and 1K blocks that yield a maximum swap space of 32GB and you want 39GB. You need to increase swchunk to 4096 which will allow 64GB of swapspace with maxswapchunks set to 16K.

You swap is currently underconfigured. You should at least have 25% of memory configured as swapspace (if swapmem_on=1).

[pgorn]

with this change to the ker will the system want to reboot. I know It usually wants a reboot after a change.

[A. Clay Stephenson]

Maxswapchunks is not dynamic; a reboot will be needed.

[pgorn]

Thanks Clay you are always a lot of help