[openstack-dev] Disk space requirement - any way to lower it a little?

Ben Nemec openstack at nemebean.com
Thu Jul 19 17:14:35 UTC 2018

On 07/19/2018 11:55 AM, Paul Belanger wrote:
> On Thu, Jul 19, 2018 at 05:30:27PM +0200, Cédric Jeanneret wrote:
>> Hello,
>> While trying to get a new validation¹ in the undercloud preflight
>> checks, I hit an (not so) unexpected issue with the CI:
>> it doesn't provide flavors with the minimal requirements, at least
>> regarding the disk space.
>> A quick-fix is to disable the validations in the CI - Wes has already
>> pushed a patch for that in the upstream CI:
>> https://review.openstack.org/#/c/583275/
>> We can consider this as a quick'n'temporary fix².
>> The issue is on the RDO CI: apparently, they provide instances with
>> "only" 55G of free space, making the checks fail:
>> https://logs.rdoproject.org/17/582917/3/openstack-check/legacy-tripleo-ci-centos-7-ovb-3ctlr_1comp-featureset001-master/c9cf398/logs/undercloud/home/zuul/undercloud_install.log.txt.gz#_2018-07-17_10_23_46
>> So, the question is: would it be possible to lower the requirment to,
>> let's say, 50G? Where does that 60G³ come from?
>> Thanks for your help/feedback.
>> Cheers,
>> C.
>> ¹ https://review.openstack.org/#/c/582917/
>> ² as you might know, there's a BP for a unified validation framework,
>> and it will allow to get injected configuration in CI env in order to
>> lower the requirements if necessary:
>> https://blueprints.launchpad.net/tripleo/+spec/validation-framework
>> ³
>> http://tripleo.org/install/environments/baremetal.html#minimum-system-requirements
> Keep in mind, upstream we don't really have control over partitions of nodes, in
> some case it is a single, other multiple. I'd suggest looking more at:
>    https://docs.openstack.org/infra/manual/testing.html

And this isn't just a testing thing.  As I mentioned in the previous 
thread, real-world users often use separate partitions for some data 
(logs, for example).  Looking at the existing validation[1] I don't know 
that it would handle multiple partitions sufficiently well to turn it on 
by default.  It's only checking /var and /, and I've seen much more 
complex partition layouts than that.


> As for downstream RDO, the same is going to apply once we start adding more
> cloud providers. I would look to see if you actually need that much space for
> deployments, and make try to mock the testing of that logic.

It's also worth noting that what we can get away with in ci is not 
necessarily appropriate for production.  Being able to run a 
short-lived, single-use deployment in 50 GB doesn't mean that you could 
realistically run that on a long-lived production cloud.  Log and 
database storage tends to increase over time.  There should be a ceiling 
to how large that all grows if rotation and db cleanup is configured 
correctly, but that ceiling is much higher than anything ci is ever 
going to hit.

Anecdotally, I bumped my development flavor disk space to >50 GB because 
I ran out of space when I built containers locally.  I don't know if 
that's something we expect users to be doing, but it is definitely 
possible to exhaust 50 GB in a short period of time.

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