-------- Forwarded Message --------
Subject: RE: [EXTERNAL] [VuFind-General] solr follower empty on fail of
leader
Date: Fri, 31 Jan 2025 12:53:28 +0000
From: Demian Katz <demian.k...@villanova.edu>
To: thomas schwaerzler <thomas.schwaerz...@uibk.ac.at>, vufind general
<vufind-gene...@lists.sourceforge.net>
Thomas,
I've been running multiple leader/follower Solr instances for more than
a decade, and I've never encountered the problem you describe, nor have
I heard of anyone else in the VuFind community complaining about it.
Maybe it's worth reaching out to the broader Solr community via the
solr-user mailing list to see if anyone there has similar experiences or
theories.
If it would help, I can share my specific Solr configurations... but
from memory, I think the main differences are that we do not replicate
on startup, and we don't have a backupAfter setting at all. Is there a
compelling reason to replicate on startup? Maybe turning off that
setting would be a worthwhile experiment, in case something weird during
the startup process is somehow leading to the problem you describe.
- Demian
-----Original Message-----
From: thomas schwaerzler via VuFind-General
<vufind-gene...@lists.sourceforge.net>
Sent: Friday, January 31, 2025 7:12 AM
To: vufind general <vufind-gene...@lists.sourceforge.net>
Subject: [EXTERNAL] [VuFind-General] solr follower empty on fail of leader
we have a simple architecture with two solr inices. on leader that
collects the catalog data from our partner and has a lot of inserts and
is permanently updated.
the follower index just replicates the leader and serves to the
representing vufind page.
sometimes my productive solr slave index for our productive vufind
instance turns out to be empty.
last time that happened, the follower somehow to an version number that
was exactly the version number of the follower + 1. when i tried to
replicate manually the follower did nothing. probably because it sees
itself ahead of the leader.
i cannot reproduce how the follower got empty. i have a suspicion that
this happens, when the leader gets an error and is not reachable.
did anyone have a similar experience?
here are my solr configs:
master:
====
solr/vufind/biblio/conf/solrconfig.xml
...
<!-- added request handler: master:
https://solr.apache.org/guide/solr/latest/deployment-guide/user-managed-index-replication.html#index-replication-in-solr
-->
<requestHandler name="/replication" class="solr.ReplicationHandler" >
<lst name="leader">
<!--Replicate on 'startup' and 'commit'. 'optimize' is also a
valid value for replicateAfter. -->
<str name="replicateAfter">startup</str>
<str name="replicateAfter">commit</str>
<str name="replicateAfter">optimize</str>
<!--Create a backup after 'optimize'. Other values can be
'commit', 'startup'. It is possible to have multiple entries of this
config string. Note that this is just for backup, replication does not
require this. -->
<str name="backupAfter">startup</str>
<!-- changed: no space left on device. testing remove
backup after commit: -->
<!-- str name="backupAfter">commit</str -->
<!--If configuration files need to be replicated give the
names here, separated by comma -->
<str name="confFiles">schema.xml,stopwords.txt,elevate.xml</str>
<!--The default value of reservation is 10 secs.See the
documentation below . Normally , you should not need to specify this -->
<str name="commitReserveDuration">00:00:10</str>
</lst>
<int name="maxNumberOfBackups">1</int>
</requestHandler>
follower:
=======
<!-- slave to "seamast" master: -->
<requestHandler name="/replication" class="solr.ReplicationHandler" >
<lst name="follower">
<str
name="leaderUrl">http://ds-seamast.uibk.ac.at:8986/solr/biblio</str>
<!-- str name="pollInterval">00:13:07</str -->
<str name="pollInterval">00:17:13</str>
<str name="compression">internal</str>
<str name="httpConnTimeout">20000</str>
<str name="httpReadTimeout">20000</str>
</lst>
</requestHandler>
<!-- end replication slave config -->
best
tom.
--
Thomas Schwaerzler
Digital Services Department
University Innsbruck Library
6020 Innsbruck - Innrain 52 - Austria
Phone: ++43-(0)512-507-25406
Fax: ++43-(0)512-507-25449
Email: <thomas.schwaerz...@uibk.ac.at>
URL: http://www.uibk.ac.at/ulb/ds
OpenPGP key: 0x2BD592C2, Key fingerprint = A17C 26AE FB4B BED6 7907 5DFC
5840 AB43 2BD5 92C2
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