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Posted to dev@nifi.apache.org by Ron Isaacson <is...@gmail.com> on 2018/07/25 22:29:54 UTC

Swappiness recommendation

Hello,

Looking at the System Administrator’s Guide
<https://nifi.apache.org/docs/nifi-docs/html/administration-guide.html>, I
see that you recommend setting vm.swappiness = 0 in /etc/sysctl.conf. This
is fine in most cases, but must be avoided on RHEL 6.4 through 6.7.

On RedHat kernels pre-2.6.32-642, there's a bug which can cause the OOM
killer to aggressively kill processes even when RAM is still available and
swap is unused. See this RedHat article
<https://access.redhat.com/solutions/1149413> for more information. (A
RedHat support login is required; if you don't have one, please contact me
off-list.)

I kindly recommend you add a note to your docs advising users not to apply
this setting on affected kernels. Thank you!

  - Ron

Re: Swappiness recommendation

Posted by Andy LoPresto <al...@apache.org>.

Thanks for your research and reaching out on this, Ron. If you would like, you can open a Jira to incorporate this information in the docs here [1], or just reply here that you’re not interested and one of our community members will take this task.

[1] https://issues.apache.org/jira/secure/CreateIssue!default.jspa <https://issues.apache.org/jira/secure/CreateIssue!default.jspa>


Andy LoPresto
alopresto@apache.org
alopresto.apache@gmail.com
PGP Fingerprint: 70EC B3E5 98A6 5A3F D3C4  BACE 3C6E F65B 2F7D EF69

> On Jul 25, 2018, at 3:29 PM, Ron Isaacson <is...@gmail.com> wrote:
> 
> Hello,
> 
> Looking at the System Administrator’s Guide
> <https://nifi.apache.org/docs/nifi-docs/html/administration-guide.html>, I
> see that you recommend setting vm.swappiness = 0 in /etc/sysctl.conf. This
> is fine in most cases, but must be avoided on RHEL 6.4 through 6.7.
> 
> On RedHat kernels pre-2.6.32-642, there's a bug which can cause the OOM
> killer to aggressively kill processes even when RAM is still available and
> swap is unused. See this RedHat article
> <https://access.redhat.com/solutions/1149413> for more information. (A
> RedHat support login is required; if you don't have one, please contact me
> off-list.)
> 
> I kindly recommend you add a note to your docs advising users not to apply
> this setting on affected kernels. Thank you!
> 
>  - Ron