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Hadoop >> mail # user >> namenode format error


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Re: namenode format error

On Apr 13, 2011, at 12:38 PM, Jeffrey Wang wrote:
> It's just in my home directory, which is an NFS mount. I moved it off NFS and it seems to work fine. Is there some reason it doesn't work with NFS?
Locking on NFS--regardless of application--is a dice roll, especially when client/server are different OSes and platforms.  Heck even when they are the same, it might not work.  For example, on some older Linux kernels, flock() on NFS only created a lock locally and didn't tell the NFS server, allowing another client to claim a lock!  (IIRC, fcntl did work...)

Best bet is to make sure rpc.lockd (or whatever daemon provides NFS locking) is running/working and to use the highest compatible version of NFS.  NFSv4, in particular, has file locking built into the protocol rather than as an 'external' service.