# Qserv core\* files causing docker to fail to start

**URL:** <https://www.rubin.community/t/qserv-core-files-causing-docker-to-fail-to-start/4585>\
**Category:** Data Management\
**Created:** [December 4, 2020, 12:18pm UTC](https://www.rubin.community/t/qserv-core-files-causing-docker-to-fail-to-start/4585 "2020-12-04T12:18:53Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![craig\_manzi](https://avatars.discourse-cdn.com/v4/letter/c/7cd45c/32.png) [@craig\_manzi](https://www.rubin.community/u/craig_manzi)\
**Post date:** [December 4, 2020, 12:18pm UTC](https://www.rubin.community/t/qserv-core-files-causing-docker-to-fail-to-start/4585/1 "2020-12-04T12:18:53Z")

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Dear Qserv developers,

I have recently taken over a test install of Qserv from Teng  
(One of his previous posts - [Installing and testing latest version of Qserv in Docker](http://www.rubin.community/t/installing-and-testing-latest-version-of-qserv-in-docker/4093))  
and have run into an issue involving very large (2.5G) core\* files being generated locally on the master container. Which then stops the container from starting back up as it is out of disk space.

I was able to get around this by copying out the core files to somewhere local  
`# docker cp master.localdomain:/qserv/core* /somewhere_local`

Then I was able to bring up the container and delete the core file.  
`docker start master.localdomain && docker exec -it master.localdomain rm -rf /qserv/core.2277`

I was just wondering if there was any way of moving the location of these core files?  
There are a few mounted volumes that are present on the container, so an easy solution would be to dump them there if at all possible.

Many thanks,  
Craig

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**Author:** ![fritzm](https://sea2.discourse-cdn.com/flex002/user_avatar/www.rubin.community/fritzm/32/32_2.png) [@fritzm](https://www.rubin.community/u/fritzm)\
**Post date:** [December 4, 2020, 5:03pm UTC](https://www.rubin.community/t/qserv-core-files-causing-docker-to-fail-to-start/4585/2 "2020-12-04T17:03:49Z")

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Hi Craig,

Since Docker containers all share the kernel of the host node, core file location is mediated by the kernel `core_pattern` setting for the host node and is not per-container. You can investigate how this might be set on your host node (it differs somewhat between Linux distributions, but for many may be set via `/proc/sys/kernel/core_pattern`.)

We could also investigate options to prevent the Qserv containers from generating core files _at all_, but this begs the question: how often is the system dumping core at your site, and can we assist in identifying the underlying problem?

cheers,  
–FritzM.

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**Author:** ![ktl](https://sea2.discourse-cdn.com/flex002/user_avatar/www.rubin.community/ktl/32/1373_2.png) [@ktl](https://www.rubin.community/u/ktl)\
**Post date:** [December 4, 2020, 7:25pm UTC](https://www.rubin.community/t/qserv-core-files-causing-docker-to-fail-to-start/4585/3 "2020-12-04T19:25:46Z")

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One note: wherever the core file is dumped, you can mount a host filesystem volume (or network volume) at that spot to avoid filling the container’s filesystem. But as Fritz says, not having a core dump at all is the best solution 🙂

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**Author:** ![craig\_manzi](https://avatars.discourse-cdn.com/v4/letter/c/7cd45c/32.png) [@craig\_manzi](https://www.rubin.community/u/craig_manzi)\
**Post date:** [January 7, 2021, 2:02pm UTC](https://www.rubin.community/t/qserv-core-files-causing-docker-to-fail-to-start/4585/4 "2021-01-07T14:02:16Z")

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Happy new year.

Thank you both for replying.  
Thankfully it appears this has just been a once-off, but if I run into it again I can let you know if I need some assistance in narrowing down what the cause might be.

A bit more Googling led me to this: [https://unix.stackexchange.com/questions/192716/how-to-set-the-core-dump-file-location-and-name](https://unix.stackexchange.com/questions/192716/how-to-set-the-core-dump-file-location-and-name)  
Which mentions that it is possible to set a core file size limit which might also be useful.

Cheers,  
Craig