Redis & Memcached (in-memory stores)

Distro support

Two-family skill. Both stores ship in the base repositories of every supported distro; the split that matters is the package name (and on RHEL the optional redis6/redis7 Application Stream module) and the Memcached defaults file (/etc/memcached.conf on Debian vs /etc/sysconfig/memcached on RHEL). The body below uses the Debian/Ubuntu paths; full RHEL detail is in references/redis-reference.md and references/memcached-reference.md.