Friday, September 13, 2013

Gradual Adjustments: Back to school, epilepsy medication, and DB2

This week school started again for the kids (and parents). It means to adjust to getting up early in the morning (where is the extra hour of sleep?), getting used to new and different schedules, and coping with homework. It is a process that isn't done in the blink of an eye, but which takes time. Most adjustments are "in the system" within a day or two, the rest is a matter of few weeks until everybody is really back in school mode/mood.

As I wrote before, one of my sons has/had epilepsy. Since middle of June we are happy to phase out his medication. Every 4-5 weeks we are reducing the dose of tablets he has to take, so that his body can adjust to the changed "chemical cocktail". After each change it takes a week to get used to it, then the remaining 3-4 weeks to really adapt to the new dose. Getting rid of medication is not an abrupt event, it takes a while.

Guess what DB2' autonomic features, especially the self-tuning memory manager (STMM) are doing? For a change in the workload characteristics STMM tries to adjust the configuration, the amount of available memory for different consumers. First it usually is a bigger adjustment, then it gradually moves to the final state. In a pureScale environment, previously a single member was in charge of choosing the memory configuration if STMM was active. Starting with DB2 10.5, you can specify whether each member is adjusting the memory configuration on its own, or a single member should do it and whether you pick that member or DB2 dynamically picks it.
So is it like "back to school"? I guess not, every family member has to adjust at the same pace and over night...

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