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https://issues.apache.org/jira/browse/MESOS-8339?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Benjamin Mahler updated MESOS-8339:
-----------------------------------
Shepherd: Benjamin Mahler
> Quota headroom may be insufficiently held when role has more reservation than
> quota.
> ------------------------------------------------------------------------------------
>
> Key: MESOS-8339
> URL: https://issues.apache.org/jira/browse/MESOS-8339
> Project: Mesos
> Issue Type: Bug
> Components: allocation
> Reporter: Meng Zhu
> Assignee: Meng Zhu
> Labels: multitenancy
>
> If a role has more reservation than its quota, the current quota headroom
> calculation is insufficient in guaranteeing quota allocation.
> Consider, role `A` with 100 (units of resource, same below) reservation and
> 10 quota and role `B` with no reservation and 90 quota. Let's say there is no
> allocation yet. The existing allocator would calculate that the required
> headroom is 100. And since unallocated quota role reserved resource is also
> 100, no additional resources would be held back for the headroom.
> While role `A` would have no problem getting its quota satisfied. Role `B`
> may have difficulty getting any resources because the "headroom" can only be
> allocated to `A`.
> The solution is to calculate per-role headroom before aggregating the
> quantity. And unallocated reservations should not count towards quota
> headroom. In the above case. The headroom for role `A` should be zero, the
> headroom for role `B` should be 90. Thus the aggregated headroom will be `90`.
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