On Wed, Oct 13, 2010 at 5:01 PM, Thanh Do <than...@cs.wisc.edu> 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? > of course, not. The scanner is always alive. It paces itself so that it scans all the blocks in 3 weeks. So if a datanode has just 210 blocks, it would be scanning about 10 a day. Raghu. > Thanks a lot, > Thanh > >
