Transparent Huge Pages

When you are running Couchbase on an operating system that is based on Red Hat Enterprise Linux, Transparent Huge Pages (THP) should be disabled on all server nodes, since it known to cause delays in cluster management.

The potential status of THP configuration is one of the following:

• always: Always use THP for any running process.
• madvise: THP is used only in memory regions which explicitly request it using MADV_HUGEPAGE and madvise.
• never: THP is never used for any running process.

If your Couchbase Server nodes also run processes which will use madvise to request THP then madvise is an acceptable setting, otherwise the recommended configuration is never.

Do not operate your Couchbase Server cluster nodes with the THP configuration set to always.

For further information about THP, see https://docs.couchbase.com/server/current/install/thp-disable.html.

Swap Space

On Linux, swap space is used when the 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. Swappiness indicates how frequently a system uses the swap space based on RAM usage. The swappiness range is from 0 to 100 where, by default, most Linux platforms have swappiness set to 60. For the optimal Couchbase Server operations, set the swappiness to 0 (zero).

For further information about swap space, see https://docs.couchbase.com/server/current/install/install-swap-space.html.