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From Adrian Hamza <adrian.ha...@hotmail.com>
Subject RE: Running zookeeper with journaling disabled on an ext4
Date Wed, 21 Oct 2015 18:21:05 GMT
Zookeeper fsyncs the write requests to disk before acknowledging the writes as successful.
Isn't that preventing what you described from happening?

> From: ivank@apache.org
> Date: Wed, 21 Oct 2015 17:47:08 +0000
> Subject: Re: Running zookeeper with journaling disabled on an ext4
> To: user@zookeeper.apache.org
> 
> >
> > What's your opinion on running Zookeeper with file system journaling
> > disabled on an EXT4 file system?
> > We need every ounce of performance out of it, and I believe given the
> > Zookeeper implementation (operations are logged, majority quorum is
> > required for succeeding, checkpoints are swapped only after being complete)
> > I feel that EXT4 journaling is redundant. Disabling EXT4 journaling could
> > improve performance. We have 5 servers in a Zookeeper ensemble. Am I
> > missing something or this should be fine?
> 
> I would recommend against it. With ext4 journalling disabled, a server
> crash will likely lose data, unless you have all write caching disabled. If
> you have all write caching disabled, I'd expect to see worse performance
> for all applications. It's not much safer than running in a ramdisk.
> 
> -Ivan
 		 	   		  
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