SSLSessionCacheDirective
Description: Type of the global/inter-process SSL Session Cache
Syntax: SSLSessionCache
type
Default: SSLSessionCache none
Context: server config
Status: Extension
Module: mod_ssl
This configures the storage type of the global/inter-process SSL Session Cache. This cache is an optional facility which speeds up parallel request processing. For requests to the same server process (via HTTP keep-alive), OpenSSL already caches the SSL session information locally. But because modern clients request inlined images and other data via parallel requests (usually up to four parallel requests are common) those requests are served by
different pre-forked server processes. Here an inter-process cache helps to avoid unneccessary session handshakes.
The following two storage
types are currently supported:
- none This is the default and just disables the global/inter-process Session Cache. There is no drawback in functionality, but a noticeable speed penalty can be observed.
- dbm:/path/to/datafile This makes use of a DBM hashfile on the local disk to synchronize the local OpenSSL memory caches of the server processes. The slight increase in I/O on the server results in a visible request speedup for your clients, so this type of storage is generally recommended.
- shm:/path/to/datafile[(size)] This makes use of a high-performance hash table (approx. size bytes in size) inside a shared memory segment in RAM (established via /path/to/datafile) to synchronize the local OpenSSL memory caches of the server processes. This storage type is not available on all platforms.
Examples
SSLSessionCache dbm:/usr/local/apache/logs/ssl_gcache_data
SSLSessionCache shm:/usr/local/apache/logs/ssl_gcache_data(512000)
