Thanks very much for the clarification. So, we'd i guess ideally set the block size equal to the transfer rate for optimum results.
If seek time has to be 0.5% of transfer time would i set my block size at 200MB (higher than transfer rate)? Conversely if seek time has to be 2% of transfer time would i still set my block size at 100MB? On Wed, Feb 22, 2012 at 8:16 PM, Praveen Sripati <praveensrip...@gmail.com>wrote: > Seek time is ~ 10ms. If seek time has to be 1% of the transfer time then > transfer time has to be ~ 1000 ms (1s). > > In ~ 1000 ms (1s) with a transfer rate of 100 MB/s, a block of 100MB can > be read. > > Praveen > > On Wed, Feb 22, 2012 at 11:22 AM, viva v <vivamail...@gmail.com> wrote: > >> Have just started getting familiar with Hadoop & HDFS. Reading Tom >> White's book. >> >> The book describes an example related to HDFS block size. Here's a >> verbatim excerpt from the book >> >> "If the seek time is around 10 ms, and the transfer rate is 100 MB/s, >> then to make the seek time 1% of the transfer time, we need to make the >> block size around 100 MB." >> >> I can't seem to understand how we arrived at the fact that block size >> shold be 100MB. >> >> Could someone please help me understand? >> >> Thanks >> Viva >> > >
