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From Jon Haddad <>
Subject Re: Data Loss irreparabley so
Date Thu, 27 Jul 2017 17:37:26 GMT
We (The Last Pickle) maintain an open source tool to help manage repairs across your clusters
called Reaper.  It’s a lot easier to set up and manage than trying to manage it through
cron. <>
> On Jul 27, 2017, at 12:38 AM, Daniel Hölbling-Inzko <>
> In that vein, Cassandra support Auto compaction and incremental repair. 
> Does this mean I have to set up cron jobs on each node to do a nodetool repair or is
this taken care of by Cassandra anyways?
> How often should I run nodetool repair
> Greetings Daniel
> Jeff Jirsa < <>> schrieb am Do.
27. Juli 2017 um 07:48:
> On 2017-07-25 15:49 (-0700), Roger Warner < <>>
> > This is a quick informational question.     I know that Cassandra can detect failures
of nodes and repair them given replication and multiple DC.
> >
> > My question is can Cassandra tell if data was lost after a failure and node(s) “fixed”
and resumed operation?
> >
> Sorta concerned by the way you're asking this - Cassandra doesn't "fix" failed nodes.
It can route requests around a down node, but the "fixing" is entirely manual.
> If you have a node go down temporarily, and it comes back up (with it's disk intact),
you can see it "repair" data with a combination of active (anti-entropy) repair via nodetool
repair, or by watching 'nodetool netstats' and see the read repair counters increase over
time (which will happen naturally as data is requested and mismatches are detected in the
data, based on your consistency level).
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