[jira] [Commented] (MESOS-3421) Support sharing persistent volumes across task instances

["Anindya Sinha (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/MESOS-3421?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14944233#comment-14944233 ] 

Anindya Sinha commented on MESOS-3421:
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I am looking into this JIRA and had an observation, and was hoping if someone can throw some light on the use case of sharing of other resource types:

In addition to shareable persistent volume disk resource, I understand the use case of non-persistent volume disk resources being shared. Persistent volumes are gc-ed only after a DESTROY is done, whereas non-persistent volumes can be gc-ed only after all containers using that persistent volume terminates; and in both cases, multiple task containers on the same agent can have access to the same volume simultaneously.

However, what other resource types can be shared? Is there any use case of sharing cpu, mem, ports and disk (without a volume associated with it) being shareable? IIUC, shareable resources are relevant not for resource types, but when a discrete "thing" is associated with the resource type. eg. I understand sharing a "volume" (persistent or non-persistent) being a valid scenario for disk resource, but not sharing just a disk resource (since that is more like a pool from which tasks are given chunks). Maybe I am just misunderstanding the use cases here.

Regarding *custom* resource types, are there examples which illustrate sharing of resource types?

If the above is accurate, we should focus on "shareable" attribute in "DiskInfo" as opposed to it being a part of the higher level "Resource". If and when there is another resource type identified that can be shared, we should have it as a part of a subsection within Resource protobuf (similar to DiskInfo).

> Support sharing persistent volumes across task instances
> --------------------------------------------------------
>
>                 Key: MESOS-3421
>                 URL: https://issues.apache.org/jira/browse/MESOS-3421
>             Project: Mesos
>          Issue Type: Improvement
>          Components: general
>    Affects Versions: 0.23.0
>            Reporter: Anindya Sinha
>            Assignee: Anindya Sinha
>
> A service that needs persistent volume needs to have access to the same persistent volume (RW) from multiple task(s) instances on the same agent node. Currently, a persistent volume once offered to the framework(s) can be scheduled to a task and until that tasks terminates, that persistent volume cannot be used by another task.
> Explore providing the capability of sharing persistent volumes across task instances scheduled on a single agent node.



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