[Pdns-users] sqlite3 backend errors (possible in relation to using sqlite3-rsync)

[Jacob de Brouwer]

Hi powerdns mailinglist,

We have some weird behavior and want to know if this is either a misconfiguration on our end or a bug.

We have build a DNS setup consisting of a single, hidden master server which uses sqlite3 to administrater DNS zone information.
This sqlite backend database is then replicated to three pdns authorative servers by using sqlite3-rsync. (see: https://www.sqlite.org/rsync.html)
This sync seems to be running fine, and the authorative servers are handling the syncing of this file without issues. We do however see some strange behaviour in the logs from time to time:

Jan 27 15:16:54 pdns_server[880067]: Backend reported permanent error which prevented lookup (GSQLBackend unable to lookup <DOMAINNAME HIDDEN>l|ANY':Error while retrieving SQLite query results: database disk image is malformed (11)), aborting

Jan 27 13:27:39 pdns_server[880067]: Backend error: GSQLBackend unable to find before/after (before) for domain_id 1988 and qname '2u13167hsjsu39hssbaivjsli8bb47lv: Error while retrieving SQLite query results: database disk image is malformed (11)

When we do integrity checks on the sqlite file, they return without issues. So the data on disk seems to be intact and not seem corrupted like the error message seems to indicate.

root at nsauth-3 ~ #  sqlite3 /var/lib/powerdns/pdns_sql3.db
SQLite version 3.40.1 2022-12-28 14:03:47
Enter ".help" for usage hints.
sqlite> pragma quik_check;
sqlite> pragma quick_check;
ok
sqlite> pragma integrity_check;
ok
sqlite>

We also do not have customers reporting issues or see any other abnormal behavior in the operations of the authorative server.

Could someone advise us on how to further troubleshoot this issue?
Met vriendelijke groet,

JACOB DE BROUWER
NETWORK ENGINEER
Interconnect Services B.V.

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