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Sybase IQ Main cache in Use: Critical 100%

April 15, 2013

Even if Sybase Control Center heat Chart Perspective report Sybase IQ main cache in use to be in critical condition with 100% utilization, the main cache is in good shape. This is because Sybase IQ will leave all buffers in memory until the buffer needs to be used for some other data.

 

 

The following is an textual extract from “Sybase, System Administration Guide: Volume 1, Sybase IQ 15.2” page 595

 

“Number of buffers in use. Normally this will be 100% because the buffer manager leaves
buffers in memory until the buffer needs to be used for some other data. In general, the
buffers used and buffers locked numbers are meaningless, because IQ uses buffers as
aggressively and efficiently as it can.
Note: This value will grow to maximum number of buffers that fit in the main buffer cache.
The number increments whenever a buffer is allocated, but only decrements when a buffer
is destroyed, not when it is unlocked or flushed. Objects in the temporary cache release
their buffers when they are finished, but in the main cache, IQ may or may not destroy the
buffers because as long as a buffer is unlocked, it is available for reuse, whether it is empty,
contains data, or contains destroyed data.”

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