BigSav logger (2)

Big saves are performed four times a day.  Scalar readings and settings
are scaled and saved in this logger.  

Only the first array element of an array device is saved in this logger
More than 100,000 readings and settings are logged during each big
save.  

It takes several minutes to process and log the data after the big save 
finishes.  Logged buckets (capacity: 250 points) are read into memory, a
single point is added, and the logged bucket is rewritten, since all of
these buckets cannot be held in memory.  These data buckets are not compressed.

See BigRay for information about array logging of big save readings and
settings.

Recall that big saves save only operational front-ends.  Some devices or 
properties are excluded from big saves.  See Save/Restore property on D80.

Since June 10, 2008