diff --git a/includes/cache.inc b/includes/cache.inc
index 09f4d753f96b4f4a627b0d408dee386d238d6ca4..207bf6615c02b292febeb7d3c708d03268093766 100644
--- a/includes/cache.inc
+++ b/includes/cache.inc
@@ -98,9 +98,11 @@ function cache_get_multiple(array &$cids, $bin = 'cache') {
  * @param $data
  *   The data to store in the cache. Complex data types will be automatically
  *   serialized before insertion. Strings will be stored as plain text and are
- *   not serialized.
+ *   not serialized. Some storage engines only allow objects up to a maximum of
+ *   1MB in size to be stored by default. When caching large arrays or similar,
+ *   take care to ensure $data does not exceed this size.
  * @param $bin
- *   The cache bin to store the data in. Valid core values are:
+ *   (optional) The cache bin to store the data in. Valid core values are:
  *   - cache: (default) Generic cache storage bin (used for theme registry,
  *     locale date, list of simpletest tests, etc.).
  *   - cache_block: Stores the content of various blocks.
@@ -119,7 +121,7 @@ function cache_get_multiple(array &$cids, $bin = 'cache') {
  *     the administrator panel.
  *   - cache_path: Stores the system paths that have an alias.
  * @param $expire
- *   One of the following values:
+ *   (optional) One of the following values:
  *   - CACHE_PERMANENT: Indicates that the item should never be removed unless
  *     explicitly told to using cache_clear_all() with a cache ID.
  *   - CACHE_TEMPORARY: Indicates that the item should be removed at the next
@@ -254,10 +256,12 @@ function getMultiple(&$cids);
    *   The cache ID of the data to store.
    * @param $data
    *   The data to store in the cache. Complex data types will be automatically
-   *   serialized before insertion.
-   *   Strings will be stored as plain text and not serialized.
+   *   serialized before insertion. Strings will be stored as plain text and not
+   *   serialized. Some storage engines only allow objects up to a maximum of
+   *   1MB in size to be stored by default. When caching large arrays or
+   *   similar, take care to ensure $data does not exceed this size.
    * @param $expire
-   *   One of the following values:
+   *   (optional) One of the following values:
    *   - CACHE_PERMANENT: Indicates that the item should never be removed unless
    *     explicitly told to using cache_clear_all() with a cache ID.
    *   - CACHE_TEMPORARY: Indicates that the item should be removed at the next