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Dynamic Managing the swap file creation & deletion - Swapd

Swap or virtual memory is a technique used to write some memory content, not used at the moment, to the hard disk to make room for a process which needs more memory now. swap is said to be 1000 times slower than having "real", physical memory.

By using swap space, programs can be started even when the memory is used to its maximum without having to shut down processes first. This also make a good buffer for when peaks of memory usage occur. Linux can add swap space in two ways, either as a swap file within the file system or as a separate partition.

Swapd is a dynamic swapping manager for Linux (Swapd works with Linux kernels version 2.4.23 or higher). Swapd provides the system with as much swap space (virtual memory) as is required at a particular time by dynamically creating swap files. This is more convenient than using fixed swap files and/or partitions because they ..

  * Swap space are unused most of the time and are just taking up disk space
  * Provide a limited amount of virtual memory.

On systems that have constant need for virtual memory it would still be wise to use a swap partition in parallel with dynamic swapping, since swap partitions provide much faster access than swap files.

Swapd Installation:
Open terminal from Applications > Accessories > Terminal, and type following command to install
sudo apt-get install swapd
After successful installation, start the swapd demon using command /etc/init.d/swapd start and finally take a look at /etc/swapd.conf and change what is necessary as per your requirement.

NOTE: The first thing you should know is that Linux supports only 8 swaps (either files or partitions) by default. If you intend to take full advantage of dynamic swapping, you should recompile your kernel (In include/linux/swap.h under Linux source directory change the value of MAX_SWAPFILES from 8 to 256. This defines how many swaps you will be able to have.) to support more swaps, or get one which already does.


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