Routine repair on single node installations?

[Troels Arvin <tr...@arvin.dk>]

Hello,

I think I understand why one needs to regularly run "nodetool repair" on 
normal Cassandra installations with more than one node.

But am I right about the following?
In single-node Cassandra installations, it is irrelevant to run 
"nodetool repair" cron jobs.

-- 
Regards,
Troels Arvin

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Re: Routine repair on single node installations?

[Jeff Jirsa <jj...@gmail.com>]

> On Feb 1, 2019, at 1:51 AM, Troels Arvin <tr...@arvin.dk> wrote:
> 
> Hello,
> 
> I think I understand why one needs to regularly run "nodetool repair" on normal Cassandra installations with more than one node.

For people following along at home, the reason is to make sure tombstones make it to all hosts before gc grace seconds expires 

> 
> But am I right about the following?
> In single-node Cassandra installations, it is irrelevant to run "nodetool repair" cron jobs.

It shouldnt be needed, because the tombstones must already be there.

One weird edge case note though: there is a setting on some versions of Cassandra that only allows Cassandra to purge tombstones that have been repaired. If you set that on a single node cluster, it’s impossible to satisfy that condition, since you can’t repair one host, so you can’t purge any of those tombstones. It’s effectively like setting infinite gc grace. If you’ve turned that setting on for a single host cluster, be sure to turn it off.
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