Set nova config max_concurrent_disk_ops

[Gerry Kopec]

In previous releases, stx-nova was patched to support option concurrent_disk_operations. This limited parallelism of heavy I/O download operations (e.g. image convert, glance downloads) and was set to 2. This option is not available in stable/stein but equivalent functionality is provided by option max_concurrent_disk_ops. See commit:
https://review.opendev.org/#/c/609180/

We should investigate taking advantage of the nova feature to handle heavy i/o stress scenarios. Note that nova defaults the feature to off so we'll need to override it to the desired setting.

I haven't observed a test scenario where this is problem yet so that would also have to be established.

[Ghada Khalil (gkhalil)]

Marking as stx.3.0 as this is likely a good nova feature to explore using in stx. But this doesn't sound critical enough to hold up stx.2.0

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/688320

[Ghada Khalil (gkhalil)]

As per community review on 12/11, the recommendation is to cherry-pick this fix to r/stx.3.0 for the first maintenance release. Therefore, changing the priority to High (only high priority bugs are cherrypicked after the final compile).

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/688320
Committed: https://git.openstack.org/cgit/starlingx/openstack-armada-app/commit/?id=1a9290dde1d9df938c08893ac94cbc8de248e37a
Submitter: Zuul
Branch: master

commit 1a9290dde1d9df938c08893ac94cbc8de248e37a
Author: zhipengl <email address hidden>
Date: Mon Oct 14 19:59:55 2019 +0800

    Set nova config max_concurrent_disk_ops

    Current config "concurrent_disk_operations" is not used anymore.
    Change it to "max_concurrent_disk_ops" as related patch already
    merged since stein.
    https://review.opendev.org/#/c/609180/

    Closes-Bug: #1835559

    Change-Id: I98ce7cee6ef133dbbe70f7af89494ee6e6c021f9
    Signed-off-by: Zhipeng Liu <email address hidden>

[Ghada Khalil (gkhalil)]

@Zhipeng, thank you for getting the fix merged in stx master. Please cherrypick the change to the r/stx.3.0 branch at your earliest convenience. This bug is tagged for stx.3.0.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: r/stx.3.0
Review: https://review.opendev.org/707280

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/707280
Committed: https://git.openstack.org/cgit/starlingx/openstack-armada-app/commit/?id=863f4b9733d3d4f4fd490606a94b84cfdaf2df2c
Submitter: Zuul
Branch: r/stx.3.0

commit 863f4b9733d3d4f4fd490606a94b84cfdaf2df2c
Author: zhipengl <email address hidden>
Date: Mon Oct 14 19:59:55 2019 +0800

    Set nova config max_concurrent_disk_ops

    Current config "concurrent_disk_operations" is not used anymore.
    Change it to "max_concurrent_disk_ops" as related patch already
    merged since stein.
    https://review.opendev.org/#/c/609180/

    Closes-Bug: #1835559

    Change-Id: I98ce7cee6ef133dbbe70f7af89494ee6e6c021f9
    Signed-off-by: Zhipeng Liu <email address hidden>
    (cherry picked from commit 1a9290dde1d9df938c08893ac94cbc8de248e37a)