Thomas,
This post from Ryan Svihla has a few notes in it that may or may not be
useful to you:
>If you read the original throttling Jira you can see that there is a hurry
up and wait component to unthrottled compaction (CASSANDRA-2156- Compaction
Throttling). Ultimately you will saturate your IO in bursts, backing up
other processes and making different bottlenecks spike up a long the way,
potentially causing something OTHER than compaction to get so far behind
that the server becomes unresponsive (such as GC).
via https://medium.com/@foundev/how-i-tune-cassandra-compaction-7c16fb0b1d99
On Mon, Jun 11, 2018 at 12:05 AM, Steinmaurer, Thomas <
thomas.steinmau...@dynatrace.com> wrote:
> Sorry, should have first looked at the source code. In case of 0, it is
> set to Double.MAX_VALUE.
>
>
>
> Thomas
>
>
>
> *From:* Steinmaurer, Thomas [mailto:thomas.steinmau...@dynatrace.com]
> *Sent:* Montag, 11. Juni 2018 08:53
> *To:* user@cassandra.apache.org
> *Subject:* compaction_throughput: Difference between 0 (unthrottled) and
> large value
>
>
>
> Hello,
>
>
>
> on a 3 node loadtest cluster with very capable machines (32 physical
> cores, 512G RAM, 20T storage (26 disk RAID)), I’m trying to max out
> compaction, thus currently testing with:
>
>
>
> concurrent_compactors: 16
>
> compaction_throughput_mb_per_sec: 0
>
>
>
> With our simulated incoming load + compaction etc., the Linux volume shows
> ~ 20 Mbyte/s Read IO + 50 Mbyte/s Write IO in AVG, constantly.
>
>
>
>
>
> Setting throughput to 0 should mean unthrottled, right? Is this really
> unthrottled from a throughput perspective and then is basically limited by
> disk capabilities only? Or should it be better set to a very high value
> instead of 0. Is there any semantical difference here?
>
>
>
>
>
> Thanks,
>
> Thomas
>
>
>
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--
*Joshua Galbraith *| Senior Software Engineer | New Relic
C: 907-209-1208 | jgalbra...@newrelic.com
