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MapReduce >> mail # user >> HDFS HA IO Fencing


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Re: HDFS HA IO Fencing
Hi Liu,

Locks are not sufficient, because there is no way to enforce a lock in a
distributed system without unbounded blocking. What you might be referring
to is a lease, but leases are still problematic unless you can put bounds
on the speed with which clocks progress on different machines, _and_ have
strict guarantees on the way each node's scheduler works. With Linux and
Java, the latter is tough.

You may want to look into QuorumJournalManager which doesn't require
setting up IO fencing.

-Todd

On Thu, Oct 25, 2012 at 1:27 AM, lei liu <[EMAIL PROTECTED]> wrote:

> I want to use HDFS HA function, I find the  IO Fencing function is
> complex in hadoop2.0. I think we can use  file lock to implement the  IO
> Fencing function, I think that is simple.
>
> Thanks,
>
> LiuLei
>

--
Todd Lipcon
Software Engineer, Cloudera