Hi Thanh, The scan period is the period that hadoop *attempts* to complete an entire node scan. That is, if it's set to 3 weeks, HDFS will try to scan each block once every 3 weeks.
Obviously, depending on the bandwidth you have made available to the scanning thread, you can specify impossibly small periods. Brian On Oct 13, 2010, at 7:01 PM, Thanh Do wrote: > 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
