Well, lucene is "write once" and then, eventually, "delete once" ;)

Ie files are eventually deleted (when they are merged away).

So when you do the incremental backup, any file not listed in the
current commit can be removed from your backup (assuming you only want
to backup the last commit).

Don't delete the files in your last backup... keep the ones that are
"in common" with your new backup as you don't need to recopy them
(they will not have changed).

Mike

On Fri, Feb 26, 2010 at 1:47 AM,  <luocan19826...@sohu.com> wrote:
> thanks for your paper,Michael McCandlessI have one quetion about thisFor all 
> other files, Lucene is "write once."This makes doing
> incremental backups very easy: Simply compare the file names.Once a
> file is written, it will never change; therefore, if you've already
> backed up that file, there's no need to copy it again.this means the number 
> of files is growing more and more.never getting less.another question:I 
> should delete the files previous I backup when I backup again. ----- 原文 ----- 
> 发件人: Michael McCandless 主 题: Re: problem about backup index file时 间: 
> 2010年2月25日  23:19:59This is likely happening because you're attempting to 
> copy a file thatIndexWriter is currently writing?You shouldn't do that (copy 
> files that are still being written) --that just wastes bytes (they aren't 
> used by the index), and causesthis failure on Windows.Instead, you should use 
> SnapshotDeletionPolicy -- it tells youspecifically which files make up the 
> latest commit point.  Those fileswill not be opened for writing (only for 
> reading, if you have anIndexReader open on that commit) and they should copy 
> just fine onwindows.The "Hot backups with Lucene" article (NOTE: I'm the 
> author) inupcoming Lucene in Action 2 revision shows how to do this -- 
> it'savailable for download from http://manning.com/hatcher3.MikeOn Thu, Feb 
> 25, 2010 at 3:15 AM,  &lt;luocan19826...@sohu.com&gt; wrote:&gt; I want 
> backup my index file,but I get the follow error.&gt; 
> java.io.IOException:&amp;nbsp;another program lock the file!&amp;nbsp;at 
> java.io.FileInputStream.readBytes(Native Method)&amp;nbsp;at 
> java.io.FileInputStream.read(Unknown Source)&amp;nbsp;at 
> com.common.Utils.copyDirectory(Utils.java:149)&amp;nbsp;at 
> com.common.Utils.copyDirectory(Utils.java:138)&amp;nbsp;at 
> com.common.Utils.copyDirectory(Utils.java:138)&amp;nbsp;at 
> com.index.IndexManager.backDataPolicy(IndexManager.java:398)&amp;nbsp;at 
> com.index.IndexManager.indexLoop(IndexManager.java:222)&amp;nbsp;at 
> com.Main$1.run(Main.java:48)&amp;nbsp;at java.lang.Thread.run(Unknown 
> Source)&gt; &amp;nbsp;&gt; How can I backup lucene file in IR 
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