Sudden drop in read cache rate - why?

Hello everyone. I'm experiencing Informix behaviour that feels weird to me. Sometimes, let's say once a week on average, read cache rate drops suddenly. Most of the time read cache rate is very high, around 99.7 percent. And all of the sudden it drops to somewhere around 50%. Then it spends few hours reaching 95% and a day or two to get over 99% level. As you've already guessed, after few more days the story repeats itself. It never happens with write cache rate, though. I never experience buffer overflow, that is "onstat -p" reports ovbuff to be zero, so I guess I have enough buffers configured. Config is: IDS 9.40UC5W2 on Solaris 9, Sun Fire V480 with 2 processors and 4 GB RAM. Thanks everyone.

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> In 32 bit servers most counters are also 32 bit and roll over when > they reach 2^32-1 (4294967295) or 2^31-1 (2147483647). If that I suppose this is the case. At this moment buffreads is around 2^30, it will reach 2^31 or 2^32 sometimes soon since it grows quite fast over time. Thanks Christian, mistery solved.