Each new threshold must be at least twice the @@thresh_hysteresis value from the next closest threshold, as shown in Figure 31-12:
Figure 31-12: Determining where to place a threshold
To see the hysteresis value for a database, use:
select @@thresh_hysteresis
In this example, a segment has a threshold set at 100 pages, and the hysteresis value for the database is 64 pages. The next threshold must be at least 100 + (2 * 64), or 228 pages.
select @@thresh_hysteresis
-----------
64
sp_addthreshold mydb, user_log_dev, 228,
sp_thresholdaction
