Backup of a Solr index

[Jörg Kiegeland]

Is there a standard way to dump the Solr index to a file or to a
directory as backup, and to import a such saved index to another Solr
index later?

Another question I have, is whether one is allowed to copy the
/data/index folder while the Solr server is still running, as easy
alternative to do a backup (may this conflict with Solr holding open
files?)?

Happy new year,
Jörg

[Charlie Jackson]

Solr indexes are file-based, so there's no need to "dump" the index to a file.

In terms of how to create backups and move those backups to other servers, check out this page http://wiki.apache.org/solr/CollectionDistribution.

Hope that helps.



-----Original Message-----
From: Jörg Kiegeland [mailto:[hidden email]]
Sent: Wednesday, January 02, 2008 3:17 AM
To: [hidden email]
Subject: Backup of a Solr index


Is there a standard way to dump the Solr index to a file or to a
directory as backup, and to import a such saved index to another Solr
index later?

Another question I have, is whether one is allowed to copy the
/data/index folder while the Solr server is still running, as easy
alternative to do a backup (may this conflict with Solr holding open
files?)?

Happy new year,
Jörg

[Mike Klaas]

If you're writing to disk, you can minimize the chance of an  
inconsistent index by hardlinking the files first (cp -l)

-Mike

On 2-Jan-08, at 8:10 AM, Charlie Jackson wrote:

> Solr indexes are file-based, so there's no need to "dump" the index  
> to a file.
>
> In terms of how to create backups and move those backups to other  
> servers, check out this page http://wiki.apache.org/solr/ 
> CollectionDistribution.
>
> Hope that helps.
>
>
>
> -----Original Message-----
> From: Jörg Kiegeland [mailto:[hidden email]]
> Sent: Wednesday, January 02, 2008 3:17 AM
> To: [hidden email]
> Subject: Backup of a Solr index
>
>
> Is there a standard way to dump the Solr index to a file or to a
> directory as backup, and to import a such saved index to another Solr
> index later?
>
> Another question I have, is whether one is allowed to copy the
> /data/index folder while the Solr server is still running, as easy
> alternative to do a backup (may this conflict with Solr holding open
> files?)?
>
> Happy new year,
> Jörg

[Jörg Kiegeland]

Charlie Jackson wrote:
> Solr indexes are file-based, so there's no need to "dump" the index to a file.
>  
But however one has first to shutdown the Solr server before copying the
index folder?

> In terms of how to create backups and move those backups to other servers, check out this page http://wiki.apache.org/solr/CollectionDistribution.
>  
It notes a script "abc", but I cannot find it in my Solr distribution
(nightly build)? Run those scripts on Windows XP?

[Charlie Jackson]

> But however one has first to shutdown the Solr server before copying the
index folder?

If you want to copy the hard files from the data/index directory, yes, you'll probably want to shut down the server first. You may be able to get away with leaving the server up but stopping any index/commit operations, but I could be wrong.

> It notes a script "abc", but I cannot find it in my Solr distribution
(nightly build)?

All of the collection distribution scripts can be found in src/scripts in the nightly build if they aren't in the bin directory of the example solr directory.

> Run those scripts on Windows XP?

No, unfortunately the Collection Distribution scripts won't work in Windows because they use Unix filesystem trickery to operate.


-----Original Message-----
From: Jörg Kiegeland [mailto:[hidden email]]
Sent: Thursday, January 03, 2008 11:00 AM
To: [hidden email]
Subject: Re: Backup of a Solr index

Charlie Jackson wrote:
> Solr indexes are file-based, so there's no need to "dump" the index to a file.
>  
But however one has first to shutdown the Solr server before copying the
index folder?

> In terms of how to create backups and move those backups to other servers, check out this page http://wiki.apache.org/solr/CollectionDistribution.
>  
It notes a script "abc", but I cannot find it in my Solr distribution
(nightly build)? Run those scripts on Windows XP?

[Jörg Kiegeland]

> If you want to copy the hard files from the data/index directory, yes, you'll probably want to shut down the server first. You may be able to get away with leaving the server up but stopping any index/commit operations, but I could be wrong.
>  
How do I stop remote clients to do index/commit operations?

Then, I think, the only solution is to retrieve all documents from the
Solr server via an all-matching query  and store the search result into
some files on hard disk. This should not get in conflict with other
clients since it is a normal "user operation", right?
If this operation would take several minutes: can other clients still
perform queries  on the server or even do updates (which should be
delayed for consistency)? Or do they get some kind of error messages (a
"No server response" would be bad..)?

[Yonik Seeley-2]

On Jan 4, 2008 8:44 AM, Jörg Kiegeland <[hidden email]> wrote:
> > If you want to copy the hard files from the data/index directory, yes, you'll probably want to shut down the server first. You may be able to get away with leaving the server up but stopping any index/commit operations, but I could be wrong.
> >
> How do I stop remote clients to do index/commit operations?

A postCommit hook (configured in solrconfig.xml) is called in a safe
place for every commit.
You could have a program as a hook that normally did nothing unless
you had previously signaled to make a copy of the index.

> Then, I think, the only solution is to retrieve all documents from the
> Solr server via an all-matching query  and store the search result into
> some files on hard disk. This should not get in conflict with other
> clients since it is a normal "user operation", right?

That's a pretty expensive way to do it, but it would work assuming all
the fields were stored.

> If this operation would take several minutes: can other clients still
> perform queries  on the server or even do updates (which should be
> delayed for consistency)?

Other clients could continue to do queries, and updates would not need
to be delayed (they won't be visible until a commit).

-Yonik

[Jörg Kiegeland]

> A postCommit hook (configured in solrconfig.xml) is called in a safe
> place for every commit.
> You could have a program as a hook that normally did nothing unless
> you had previously signaled to make a copy of the index.
>  
Then I will give the postCommit trigger a try and hope that while the
trigger is executed, the files in data/index are in a consistent state
so that I can copy them.

Do you know how this signal can be communicated to the trigger at best?
I use Solrj and would call server.commit(), and unfortunately one can
not pass a commit message which could be used as signal for the trigger.