Quick Understanding on swap

Swap Space is virtual memory, using your HDD when you run out of memory. The system swaps some of the contents out of the RAM to the HDD (swap), then bring it back when required.

In the past, when RAM was very small in the single digit of GB or less, we take the rule of 2 times the memory. But with large memory available in your Server, it may not be necessary to configure as much, as we only need as much as we can suspend to disk. I like to use between 16GB to 32GB swap

To control the tendency for the system to use the swap. Configure the vm.swappiness at /etc/sysctl.conf. It is the percentage of memory free before using swap. If you have lots of memory, you can use it as low as 10 from the default 60.

Do take a look at Quick Understanding on Swap


Another way to calculate shared memory swapping

Using ipcs utlities to find out information on shared memory utilisation which can be useful for analysing the performance of the system. Let’s says you want to measure how much memory has been swapped.

% ipcs -mu
------ Shared Memory Status --------
segments allocated 55
pages allocated 6655333
pages resident  5661034
pages swapped   947522
Swap performance: 0 attempts     0 successes

-m is “information about active shared memory segments”
-u is “Show status summary”

You would need PAGE Memory

getconf PAGESIZE

To provide us with the information in MB

echo "$((947522*4096/1024/1024)) MB"
3701 MB

Opening the Door to Big Memory

Join MemVerge, IDC, Intel, NetApp, and Penguin Computing in a webcast introducing a new category of IT that turns scarcity into abundance.

Tuesday, May 19th at 9:00 AM PST

This Webcast Introduces a New Wave of Computing: Big Memory Computing

Memory has been a wonderfully fast but scarce computing resource. This scarcity has resulted in major constraints that prevent applications from processing large amount of real-time data effectively.

These constraints are being removed by a new way of computing: Big Memory Computing. Today, the confluence of persistent memory and Big Memory software makes memory abundant, persistent and highly available. Together, they promise to make the IT world stop, think, and change the way applications are developed and deployed………

For more information, see https://www.memverge.com/opening-the-door-to-big-memory/

To register see https://us02web.zoom.us/webinar/register/WN_gDXc3wD7QtaLhMNc8PCQPg