Bug 1369589
Summary: | [RFE] Add vm.overcommit_memory check | ||
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Product: | Red Hat Satellite | Reporter: | Josh Foots <jfoots> |
Component: | Installation | Assignee: | Chris Roberts <chrobert> |
Status: | CLOSED ERRATA | QA Contact: | Daniel Lobato Garcia <dlobatog> |
Severity: | low | Docs Contact: | |
Priority: | low | ||
Version: | 6.1.9 | CC: | bbuckingham, cduryee, chrobert, dlobatog, jcallaha, oshtaier, stbenjam |
Target Milestone: | Unspecified | Keywords: | FutureFeature, Triaged |
Target Release: | Unused | ||
Hardware: | x86_64 | ||
OS: | Linux | ||
URL: | http://projects.theforeman.org/issues/16300 | ||
Whiteboard: | |||
Fixed In Version: | Doc Type: | If docs needed, set a value | |
Doc Text: | Story Points: | --- | |
Clone Of: | Environment: | ||
Last Closed: | 2018-02-21 16:54:17 UTC | Type: | Bug |
Regression: | --- | Mount Type: | --- |
Documentation: | --- | CRM: | |
Verified Versions: | Category: | --- | |
oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
Cloudforms Team: | --- | Target Upstream Version: | |
Embargoed: |
Description
Josh Foots
2016-08-23 21:03:11 UTC
add'l info: If you run a java app without Xmx set, it will ask for 1/4 of physical memory. If vm.overcommit_memory is set to 0 (default) or 1, this is fine. The OS will give the process 1/4 of memory, but will not guarantee that the full space is available. However, if vm.overcommit_memory is set to 2, it enforces that all memory allocated to processes is backed by physical memory. To try this out, you can start a VM, use >75% of memory, then run "java -version". If overcommit is set to 2, it will fail. This is not unreasonable behavior, since Java has no idea how much mem it will need without Xmx guidance, and typically it's fine to ask for more than what it actually uses. Some users set vm.overcommit_memory to 2 in order to avoid OOM conditions. However, any process that asks for more memory than it needs may not be able to execute. There are two ways to "fix" this for Satellite: * verify that overcommit is not set to 2 during pre-upgrade check * ensure that all java processes have Xmx set to something reasonable, to avoid the "25% of physical mem" default. Both of these would be good to do, but the first option is most needed. Users should not run overcommit_memory=2 on a Satellite, since it is not a tested scenario. Created redmine issue http://projects.theforeman.org/issues/16300 from this bug Verified. Tested in Satellite 6.3 - Snap 13 Some output from the CLI of what I did to verify: --- [root@tyan-gt24-13 ~]# sysctl -n vm.overcommit_memory 2 [root@tyan-gt24-13 ~]# satellite-installer This system has the vm.overcommit.memory flag enabled in sysctl. Please set this to 0 and then run the installer again. Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA.
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> For information on the advisory, and where to find the updated files, follow the link below.
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> If the solution does not work for you, open a new bug report.
>
> https://access.redhat.com/errata/RHSA-2018:0336
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