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From Zhanwei Wang <wan...@apache.org>
Subject Re: Turning off DoS protection in hawq
Date Sun, 11 Dec 2016 02:09:31 GMT
HI Ruilong

According the pervious stress test, under very high workload, OS will consider the connection
from HAWQ to HDFS as Dos and reject the connect request and then HAWQ query will fail.

After disabling CO table in HAWQ, we have significantly reduced the file write workload, I
think it is time to reconsider this OS setting.

Best Regards

Zhanwei Wang

> 在 2016年12月11日,上午8:38,Ruilong Huo <rhuo@pivotal.io> 写道:
> Hi hawq community,
> Anyone know that why we turn off DoS protection in hawq by setting
> net.ipv4.tcp_syncookies to off in /etc/sysctl.conf? Any other reason from
> hawq perspective other than below two more from operating system
> perspective?
> 1) increase the number of concurrent tcp clients
> 2) reduce cpu overhead for creating and processing the syncookies. Though
> the overhead is tiny
> BTW: HAWQ turn off DoS protection
> <http://hdb.docs.pivotal.io/210/hdb/install/install-cli.html> while
> Greenplum Database enable DoS protection
> <http://gpdb.docs.pivotal.io/4320/install_guide/prep_os_install_gpdb.html> by
> default.
> Best regards,
> Ruilong Huo

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