Adam Novak created MESOS-7420:
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Summary: Mesos slaves do not account for root disk reservation
when measuring disk resources
Key: MESOS-7420
URL: https://issues.apache.org/jira/browse/MESOS-7420
Project: Mesos
Issue Type: Bug
Components: allocation
Affects Versions: 0.23.0
Reporter: Adam Novak
Priority: Minor
The Mesos slaves measure the free disk space in their work directories, and
offer all of it.
Since the Mesos slaves run as root (in order to switch to the actual user any
given task needs to run as), they see all unused space on a given disk as free,
including space reserved for root (which is, by default, 5% of any disk).
But when the actual code that does work starts up, it probably isn't running as
root, so it will only see the unreserved free space as actually free. This is
in general about 5% less.
When running with disks that are nearly full, or if the scheduled user code
double-checks that it actually got all the free space it asked for, this can
create problems.
Mesos should not include disk space reserved for root in its offers, unless it
knows that the framework it is making the offer to is going to be running its
tasks as root.
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