The reason for using swap

[ahrin]

I think that Using Swap, Disk I/O is increased.

And The server's performance is degraded.

However, SWAP is recommended by SAP.

I would like to know why.

Thank you.

[karthikeyan_natarajan4]

Hi Hye,

Swap space  is used when the amount of physical memory (RAM) is full. If the system needs more memory resources and the RAM is full, inactive pages in memory are moved to the swap space. While swap space can help machines with a small amount of RAM, it should not be considered a replacement for more RAM. Swap space is located on hard drives, which have a slower access time than physical memory.
 
SAP recommend for swap 3 times of RAM.

regards

kartik

[Former Member]

Hi,

Please check the below two note.

Note 146289 - Parameter Recommendations for 64-Bit SAP Kernel

Note 146528 - Configuration of R/3 on hosts with much RAM

1. Swap space:

                       For the special solutions described here a large swap space is required. We recommend a swap space size of 3 to 4 times the RAM size, even though a swap space of 10 GByte or more might have to be created.

Is there any specific task happening on the server after which you have seen this increase?

Yes correct sap suggest swap configuration but why swaping is happening because the memory and the buffers that you allocated to the application is not sufficient.

To minimize operating system swapping, the configured memory size of the machine should be greater than the average memory usage of the SAP application running . If the SAP application in the virtual machine needs more memory than it has been allocated, the guest operating system paging/swapping mechanisms are invoked.Memory and swap/page file configuration of the SAP application in the virtual machine follow the same

guidelines as for native environments, and generally, you should set them to minimize guest operating system swapping. Follow existing SAP documentation and recommendations as provided in these SAP

You need to look in the memory parameters of your system.

Thanks

Rishi abrol