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From Michael McCandless <luc...@mikemccandless.com>
Subject Re: NFS, Stale File Handle Problem and my thoughts....
Date Wed, 20 Jan 2010 13:44:54 GMT
Right, you just need to make a custom IndexDeletionPolicy.  NFS makes
no effort to protect deletion of still-open files.

A simple approach is one that only deletes a commit if it's more than
XXX minutes/hours old, such that XXX is set higher than the frequency
that IndexReaders are guaranteed to have reopened.

The TestDeletionPolicy unit test in Lucene's sources has the
ExperiationTimeDeletionPolicy that you can use (but scrutinize!).

Another alternative is to simply reopen the reader whenever you hit
Stale file handle (think of it as NFS's means of notifying you that
your reader is no longer current ;) ).  But, if reopen time is
potentially long for your app, it's no good to make queries pay that
cost and the deletion policy is better.

Mike

On Wed, Jan 20, 2010 at 8:29 AM, Sertic Mirko, Bedag
<Mirko.Sertic@bedag.ch> wrote:
> Hi@all
>
>
>
> We are using Lucene 2.4.1 on Debian Linux with 2 boxes. The index is
> stored on a common NFS share. Every box has a single IndexReader
> instance, and one Box has an IndexWriter instance, adding new documents
> or deleting existing documents at a given point in time. After adding or
> deleting the documents, a IndexWriter.optimize() is called. Every box
> checks periodically with IndexReader.isCurrent if the index needs to be
> reopened.
>
>
>
> Now, we are encountering a "Stale file handle" error on box b after the
> index was modified and optimized by box a.
>
>
>
> As far as i understand the problem with NFS is that box b tries to
> open/access a file that was deleted by box a on the NFS share.
>
>
>
> The question is now, when are files deleted? Does only the index
> optimization delete files, or can files be deleted just by adding or
> removing documents from an existing index?
>
>
>
> I now that there might be a better setup with Lucene and index
> replication, but this is an existing application and we cannot change
> the architecture now. So what would be the best solution?
>
>
>
> Can I just "change" the way Lucene deletes files? I think that just
> renaming no longer needed files would be good on NFS. After every
> IndexReader has reopened the index, the renamed files can be safely
> deleted, as they are definitely no longer needed. Where would be the
> hook point? I heard something about IndexDeletionPolicy....
>
>
>
> Thanks in advance!
>
>
>
> Mirko
>
>
>
>

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