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From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Update of "MountableHDFS" by TedDunning
Date Sun, 24 Jul 2011 19:04:48 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Hadoop Wiki" for change notification.

The "MountableHDFS" page has been changed by TedDunning:
http://wiki.apache.org/hadoop/MountableHDFS?action=diff&rev1=12&rev2=13

  They are all based on the Filesystem in Userspace project FUSE ([[http://fuse.sourceforge.net/]]).
Although the Webdav-based one can be used with other webdav tools, but requires FUSE to actually
mount.
  
  Note that a great thing about FUSE is you can export a fuse mount using NFS, so you can
use fuse-dfs to mount hdfs on one machine and then export that using NFS. The bad news is
that fuse relies on the kernel's inode cache since fuse is path-based and not inode-based.
If an inode is flushed from the kernel cache on the server, NFS clients get hosed; they try
doing a read or an open with an inode the server doesn't have a mapping for and thus NFS chokes.
So, while the NFS route gets you started quickly, for production it is more robust to automount
fuse on all the machines you want access to hdfs from.
+ 
+ Also, since NFS often reorders writes, you can have write failures when you use the NFS
-> FUSE -> HDFS route.  HDFS requires that writes be sequential.
  
  == Projects ==
  

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