the time each index block is created timestamp ts 261 and cell number cn 263 are written to the index block each index entry stores particular information regarding a data cell stored in data 264 more particularly each index entry stores the url of the object stored in a data cell a hash value of the url the data cell number and the data cell size index 262 is only used at startup time to create a hash table in fast main memory the hash table is used by cache controller 44 to determine the locations of web objects in data 264 in one embodiment index 262 is implemented as a cyclic data structure of index entries cache controller 44 updates index pointer 272 and data pointer 278 in metadata 260 periodically but not each time new information is written to index 262 or data 264 the updates are only done periodically because the overhead of performing updates every time index area 262 or data area 264 are updated would be too high and would degrade performance updating index pointer 272 and data pointer 278 only periodically however creates problems when the system crashes for example if the system crashes after either index 262 or data.