“Suspending” an instance cannot release it occupied resource, but “shelving” can.

Bug #1815403 reported by lee
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
OpenStack Compute (nova)
Fix Released
Low
Stephen Finucane

Bug Description

I see server concepts from doc:
https://developer.openstack.org/api-guide/compute/server_concepts.html

From the description of "SUSPENDED" server status, it shows:
"""The server is suspended, either by request or necessity. This status appears for only the following hypervisors: XenServer/XCP, KVM, and ESXi. Administrative users may suspend a server if it is infrequently used or to perform system maintenance. When you suspend a server, its state is stored on disk, all memory is written to disk, and the server is stopped. Suspending a server is similar to placing a device in hibernation; memory and vCPUs become available to create other servers."""

However, after I suspend an active instance (named VM_1 on compute node CN_A), resource allocation of compute node CN_A has no change neither on OpenStack dashboard nor on database.

On the other hand, if I shelve this instance, the occupied resource (vCPU and memory) will be released.

Might the description of "SUSPENDED" server status should be modified as follows:
"""The server is suspended, either by request or necessity. This status appears for only the following hypervisors: XenServer/XCP, KVM, and ESXi. Administrative users may suspend a server if it is infrequently used or to perform system maintenance. When you suspend a server, its state is stored on disk, all memory is written to disk, and the server is stopped. Suspending a server is similar to placing a device in hibernation and its occupied resource will not be freed (kept for its next running). If an instance is infrequently used and the occupied resource needs to be freed to create other servers, it should be shelved."""

Revision history for this message
Matt Riedemann (mriedem) wrote :

Is this just a request for a clarification in the docs or something more, like making the suspend API optional also shelve the server? Because the former is easy, the latter is a new more complicated feature which has been discussed before:

http://lists.openstack.org/pipermail/openstack-dev/2018-September/134691.html

tags: added: docs
Changed in nova:
status: New → Confirmed
importance: Undecided → Low
tags: added: low-hanging-fruit
Revision history for this message
Matt Riedemann (mriedem) wrote :

By the way, I think the suggested re-wording in the server concepts guide is good so I've marked the bug as confirmed based on that docs clarification.

Revision history for this message
OpenStack Infra (hudson-openstack) wrote : Fix proposed to nova (master)

Fix proposed to branch: master
Review: https://review.opendev.org/663590

Changed in nova:
status: Confirmed → In Progress
Changed in nova:
assignee: nobody → Sharat Sharma (sharat-sharma)
tags: added: doc
removed: docs
Changed in nova:
assignee: Sharat Sharma (sharat-sharma) → Stephen Finucane (stephenfinucane)
Revision history for this message
OpenStack Infra (hudson-openstack) wrote : Fix merged to nova (master)

Reviewed: https://review.opendev.org/663590
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=3badb674f6604d3beca4ba557939d4fbc07f6178
Submitter: Zuul
Branch: master

commit 3badb674f6604d3beca4ba557939d4fbc07f6178
Author: Sharat Sharma <email address hidden>
Date: Thu Jun 6 06:31:27 2019 -0400

    "SUSPENDED" description changed in server_concepts guide and API REF

    The description of "SUSPENDED" server status was misguiding. Rewording
    it to make it more accurate.

    Change-Id: Ie93b3b38c2000f7e9caa3ca89dea4ec04ed15067
    Closes-Bug: #1815403

Changed in nova:
status: In Progress → Fix Released
Revision history for this message
OpenStack Infra (hudson-openstack) wrote : Related fix proposed to nova (master)

Related fix proposed to branch: master
Review: https://review.opendev.org/694329

Revision history for this message
OpenStack Infra (hudson-openstack) wrote : Related fix merged to nova (master)

Reviewed: https://review.opendev.org/694329
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=2d91a8463f194edae863b51b2224bbec5cd8c68a
Submitter: Zuul
Branch: master

commit 2d91a8463f194edae863b51b2224bbec5cd8c68a
Author: Matt Riedemann <email address hidden>
Date: Thu Nov 14 10:25:06 2019 -0500

    docs: update SUSPENDED server status wrt supported drivers

    Two things here:

    1. The API guide was missing the hyper-v driver which supports
       the suspend operation. Rather than hard-code a list of supported
       drivers in the doc, this change just links to the entry in the
       feature support matrix.

    2. The supported hypervisors mention in the API reference is removed
       because the end user using the API should not need to know or care
       what backend hypervisor on which their server is running. They can
       either suspend or not, but we don't need to mention the supporting
       drivers for that in the API reference.

    Change-Id: Ib76779a8e34b2c68b0f4af190f71576180360d0f
    Related-Bug: #1815403

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