When disk overflow is enabled, you can extend the data
grid capacity by moving cache entries out of memory and onto disk.
Use the diskOverflowEnabled property in the server properties file
to enable the disk overflow feature. When enabled, entries that do
not fit into the available memory capacity of the container servers
are stored on disk. The disk storage is not a persistent store. Entries
that are written to disk are deleted when container servers restart,
in the same way that cache entries that are stored in memory are lost
during a container server restart.
About this task
When disk overflow is enabled, it attempts to keep the most
recently used cache entries in memory. Disk overflow moves cache
entries to disk only when the number of entries in memory exceed the
maximum memory allocation, as defined by the
maxXMSize server
property. If more entries exist than can fit in memory, the least
recently used entries are moved to disk. As a result, operations
that access entries that are on disk are slower than the response
time for entries that are in memory. After the initial access, the
item stays in memory unless it becomes a least recently used entry
again. When an entry is least recently used, it is moved disk in favor
of some other entry.