This means that, when HDFS reads 1KB file from the disk, he will put the data in blocks of 64MB?
On Fri, Jun 10, 2011 at 5:00 PM, Philip Zeyliger <phi...@cloudera.com> wrote: > On Fri, Jun 10, 2011 at 8:42 AM, Pedro Costa <psdc1...@gmail.com> wrote: >> But, how can I say that a 1KB file will only use 1KB of disc space, if >> a block is configured has 64MB? In my view, if a 1KB use a block of >> 64MB, the file will occupy 64MB in the disc. > > A block of HDFS is the unit of distribution and replication, not the > unit of storage. HDFS uses the underlying file systems for physical > storage. > > -- Philip > >> >> How can you disassociate a 64MB data block from HDFS of a disk block? >> >> On Fri, Jun 10, 2011 at 5:01 PM, Marcos Ortiz <mlor...@uci.cu> wrote: >>> On 06/10/2011 10:35 AM, Pedro Costa wrote: >>> >>> Hi, >>> >>> If I define HDFS to use blocks of 64 MB, and I store in HDFS a 1KB >>> file, this file will ocupy 64MB in the HDFS? >>> >>> Thanks, >>> >>> HDFS is not very efficient storing small files, because each file is stored >>> in a block (of 64 MB in your case), and the block metadata >>> is held in memory by the NN. But you should know that this 1KB file only >>> will use 1KB of disc space. >>> >>> For small files, you can use Hadoop archives. >>> Regards >>> >>> -- >>> Marcos Luís Ortíz Valmaseda >>> Software Engineer (UCI) >>> http://marcosluis2186.posterous.com >>> http://twitter.com/marcosluis2186 >>> >>> >> > -- --------------------------- Pedro Sá da Costa @: pco...@lasige.di.fc.ul.pt @: psdc1...@gmail.com
