cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From shalom sagges <shalomsag...@gmail.com>
Subject Re: A Question About Hints
Date Mon, 04 Mar 2019 17:54:09 GMT
Hi Kenneth,

The concern is that in some cases, hints accumulate on nodes, and it takes
a while until they are delivered (multi DCs).
I see that whenever there are  a lot of hints in play,like after a rolling
restart, the cluster works harder. That's why I want to decrease the hints
delivery time.
I didn't want to change the configuration blindly and thought the community
might have some experience on this subject.

I went over the cassandra.yaml file but didn't find any information on
optimizing these attributes, just that the max_throttle is divided between
nodes in the cluster and that I should increase the
max_hints_delivery_threads because I have multi-dc deployments.

# Maximum throttle in KBs per second, per delivery thread.  This will be
# reduced proportionally to the number of nodes in the cluster.  (If there
# are two nodes in the cluster, each delivery thread will use the maximum
# rate; if there are three, each will throttle to half of the maximum,
# since we expect two nodes to be delivering hints simultaneously.)
hinted_handoff_throttle_in_kb: 1024

# Number of threads with which to deliver hints;
# Consider increasing this number when you have multi-dc deployments, since
# cross-dc handoff tends to be slower
max_hints_delivery_threads: 2


Thanks for your help!


On Mon, Mar 4, 2019 at 6:44 PM Kenneth Brotman <kenbrotman@yahoo.com.invalid>
wrote:

> What is the concern?  Why are you looking there?  The casssandra.yml file
> has some notes about it.  Did you read them?
>
>
>
> *From:* shalom sagges [mailto:shalomsagges@gmail.com]
> *Sent:* Monday, March 04, 2019 7:22 AM
> *To:* user@cassandra.apache.org
> *Subject:* A Question About Hints
>
>
>
> Hi All,
>
>
>
> Does anyone know what is the most optimal hints configuration (multiple
> DCs) in terms of
>
> max_hints_delivery_threads and hinted_handoff_throttle_in_kb?
>
> If it's different for various use cases, is there a rule of thumb I can
> work with?
>
>
>
> I found this post but it's quite old:
>
> http://www.uberobert.com/bandwidth-cassandra-hinted-handoff/
>
>
>
> Thanks!
>

Mime
View raw message