2006-11-29

Oracle Global Cache Blocks Lost

Undesirable Global Cache Statistics
The following are undesirable statistics, or statistics for which the values should always be zero or near-zero.

global cache blocks lost--This statistic reveals any block losses during transfers and high values may indicate network problems. When using an unreliable IPC protocol such as UDP, the value for 'global cache blocks lost' may be non-zero. If this is the case, then the ratio of 'global cache blocks lost' divided by 'global cache current blocks served' plus 'global cache cr blocks served' should be as small as possible. A non-zero value for 'global cache blocks lost' does not necessarily indicate a problem, because Oracle retries the block transfer operation until it is successful. Unlike TCP/IP, UDP/IP is considered unreliable because UDP/IP provides very few error recovery services.
global cache blocks corrupt--This statistic indicates whether any blocks were corrupted during transfers. High values for this statistic indicate an IPC, network, or hardware problem. "


"The Global Cache Blocks Lost Oracle metric event test checks whether a global cache request did not complete due to a timeout. A timeout is caused either by a network communication error or by a high system load."

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