[Bugs] [Bug 1540376] Tiered volume performance degrades badly after a volume stop /start or system restart.

[bugzilla at redhat.com]

https://bugzilla.redhat.com/show_bug.cgi?id=1540376



--- Comment #1 from Jeff Byers <jbyers at stonefly.com> ---
This problem appears to be related to the sqlite3 DB files
that are used for the tiering file access counters, stored on
each hot and cold tier brick in .glusterfs/<volname>.db.

When the tier is first created, these DB files do not exist,
they are created, and everything works fine.

On a stop/start or service restart, the .db files are already
present, albeit empty since I don't have cluster.write-freq-
threshold nor cluster.read-freq-threshold set, so
features.record-counters is off and nothing should be going
into the DB.

I've found that if I delete these .db files after the volume
stop, but before the volume start, the tiering performance is
normal, not degraded. Of course all of the history in these DB
files is lost. Not sure what other ramifications there are to
deleting these .db files.

When I did have one of the freq-threshold settings set, I did
see a record get added to the file, so the sqlite3 DB is
working to some degree.

The sqlite3 version I have installed is sqlite-3.6.20-
1.el6_7.2.x86_64.

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