On Mon, May 17, 2010 at 5:10 PM, jiang licht <[email protected]> wrote:
> I am considering to use a machine to save a > redundant copy of HDFS metadata through setting dfs.name.dir in > hdfs-site.xml like this (as in YDN): > > <property> > <name>dfs.name.dir</name> > <value>/home/hadoop/dfs/name,/mnt/namenode-backup</value> > <final>true</final> > </property> > > where the two folders are on different machines so that > /mnt/namenode-backup keeps a copy of hdfs file system information and its > machine can be used to replace the first machine that fails as namenode. > > So, my question is how big this hdfs metatdata will consume? I guess it is > proportional to the hdfs capacity. What ratio is that or what size will be > for 150TB hdfs? > On the order of a few GB, max (you really need double the size of your image, so it has tmp space when downloading a checkpoint or performing an upgrade). But on any disk you can buy these days you'll have plenty of space. -Todd -- Todd Lipcon Software Engineer, Cloudera
