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From: Paul Elschot <paul.elschot@xs4all.nl>
To: java-dev@lucene.apache.org
Subject: Re: After kill -9 index was corrupt
Date: Mon, 11 Sep 2006 19:13:59 +0200
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On Monday 11 September 2006 15:36, Yonik Seeley wrote:
> On 9/10/06, Chuck Williams <chuck@manawiz.com> wrote:
> > Could a kill -9 prevent data from reaching disk for files that were
> > previously closed?
> 
> No.  After a close() the OS should have all the data... the process
> may be killed but the OS will eventually flush all the buffers, etc.
> File creation is pretty much always synchronous so I have no idea how
> your problem could have happened (missing segment files).  IO error or
> something else temporarily filling up the disk?

"Pretty much always" is logically equivalent to "not always" :) , see also
below.

> If you have a power loss or crash, then that *can* cause data loss.
> There may be mount options to make more file operations synchronous,
> or you could maybe write your own Directory implementation to make
> things more synchronous.

New segments will have to be flushed/fsynced before the segments
file. This could be hidden in a Directory in case a Directory hides Lucene's
segments file.

Regards,
Paul Elschot
 

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