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SHADOW_HBMM_RTC is a system parameter that specifies, in seconds, how frequently each shadow set on this system has its modified block count compared with the reset threshold. If the modified block count exceeds the reset threshold, the bitmap for that shadow set is zeroed. This comparison is performed for all shadow sets mounted on the system that have HBMM bitmaps. The reset threshold is specified by the RESET_THRESHOLD keyword in the /POLICY qualifier of the SET SHADOW command. When the comparison is made, the modified block count might exceed the reset threshold by a small increment or by a much larger amount. The difference depends on the write activity to the volume and on the setting of this parameter. SHADOW_HBMM_RTC is a DYNAMIC parameter. It is available on Alpha and Integrity systems only.