1. Administrator's Guide
  2. Reference
  3. Tuning
  4. Turn off the swap

Turn off the swap

For best performance on a dedicated Oracle NoSQL Database server machine, turn off the swap on the machine. Oracle NoSQL Database processes are careful in their management of the memory they use to ensure that they do not exceed the RAM available on the machine.

The performance gains come from two sources:

  1. The I/O overhead due to swap is eliminated. This is especially important if the disk normally used for swap also holds the store's log files used to persist data.

  2. Reduces the CPU overhead associated with kswapd.

To turn off the swap, do not mount any swap partitions at boot time. You do this by eliminating all swap related mount entries from /etc/fstab. These are all the rows with the entry "swap" in their mount point (column 2) and file system type (column 3) entries.

You can verify that no swap space is being used by running the free command. Do this after the /etc/fstab has been modified and the machine has been rebooted: 

-bash-4.1$ free -m
            total      used      free     shared    buffers     cached
Mem:        72695     72493       202          0        289       2390
-/+ buffers/cache:    69813      2882
Swap:           0         0         0

The Swap/total cell in the above table should read 0.