DataBlockScanner scan period

[Thanh Do]

Hi again,

Could any body explain to me about the scanning period
policy of DataBlockScanner? That is who often it wake up
and scan a block file.
When looking at the code, I found

 static final long DEFAULT_SCAN_PERIOD_HOURS = 21*24L; // three weeks


but definitely it does not wake up and pick a random block
to verify every three weeks, right?

Thanks a lot,
Thanh