Why is vertica using swap space

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bacona
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Why is vertica using swap space

Post by bacona » Mon Jun 24, 2013 12:18 pm

We're witnessing growth in the swap space used by vertica processes on both a 6.1.0 and 6.1.1 cluster.

We allocate just the recommended 2GB to swap, yet over time, vertica begins to consume swap until 2GB is reached. Restarting the vertica process recovers the used swap space.

Is anyone else witnessing this consumption of swap space?

We believe it is compromising performance and is the cause or a symptom of why the Tuple Mover is failing to keep the number of ROS containers under control.
Andrew Bacon - HP ATP - Vertica Big Data Solutions V1 Certified

id10t
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Re: Why is vertica using swap space

Post by id10t » Mon Jun 24, 2013 12:56 pm

Hi!


Swappiness it is a property of system, not Vertica's. Change your swappiness to 0 and system will swap only to avoid an out of memory condition.

http://en.wikipedia.org/wiki/Swappiness
http://unixfoo.blogspot.co.il/2007/11/l ... uning.html

bacona
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Re: Why is vertica using swap space

Post by bacona » Mon Jun 24, 2013 2:26 pm

Hi sKwa,

Thanks, I should have mentioned that we've set the overcommit_memory config parameter to 0 as advised by vertica (we're running RHEL 6).

Vertica themselves state:

"Vertica process shouldn't use any swap space. If Vertica process starts using swap, there is a configuration issue.

If Vertica isn't too blame, then why does swap usage return to 0 when the vertica process is restarted?

I guess we could set swappiness to 0, that way we'll know if vertica is throwing out of memory conditions.
Andrew Bacon - HP ATP - Vertica Big Data Solutions V1 Certified

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