Skip to main content
NetApp Knowledge Base

Inconsistent Subscription Ratio Displayed on Horizon Dashboard for NetApp Backend (OpenStack Cinder)

  1. Last updated
  2. Save as PDF
Views:
20
Visibility:
Public
Votes:
0
Category:
openstack
Specialty:
virt
Last Updated:

Applies to

  • Cinder NetApp Backend (ONTAP driver)
  • Cinder with multiple controller nodes

Issue

When using OpenStack Cinder with NetApp ONTAP as the backend, the subscription ratio (overprovisioning ratio) is displayed inconsistently across different compute/controller nodes on the Horizon dashboard. Each node shows a different ratio for the same NetApp backend volume pool, resulting in confusion and risk of overprovisioning.

Example Log Output:

DEBUG cinder.scheduler.filters.capacity_filter [...] Space information for volume creation on host hyd03ctrl01@cinder-netapp#OS_G01_NA01_POOL1 (requested/avail): 600/972.8 backend_passes
DEBUG cinder.scheduler.host_manager [...] Consumed 600GB from backend: host 'hyd03ctrl02@cinder-netapp#OS_G01_NA01_POOL1': free_capacity_gb: 372.79, total_capacity_gb: 972.8, allocated_capacity_gb: 600, max_over_subscription_ratio: 1.0, provisioned_capacity_gb: 600
WARNING cinder.scheduler.filters.capacity_filter [...] Insufficient free space for thin provisioning. The ratio of provisioned capacity over total capacity 1.13 has exceeded the maximum oversubscription ratio 1.00 on host hyd03ctrl03@cinder-netapp#OS_G01_NA01_POOL1.
ERROR cinder.scheduler.flows.create_volume [...] No valid backend was found. No weighed backends available.

Symptoms:

  • Horizon dashboard shows different subscription ratios per backend per node.
  • Volume creation may succeed even when total backend capacity is exceeded (if reporting is inconsistent).
  • Overprovisioning risk when using max_over_subscription_ratio=1.0.

Sign in to view the entire content of this KB article.

New to NetApp?

Learn more about our award-winning Support

NetApp provides no representations or warranties regarding the accuracy or reliability or serviceability of any information or recommendations provided in this publication or with respect to any results that may be obtained by the use of the information or observance of any recommendations provided herein. The information in this document is distributed AS IS and the use of this information or the implementation of any recommendations or techniques herein is a customer's responsibility and depends on the customer's ability to evaluate and integrate them into the customer's operational environment. This document and the information contained herein may be used solely in connection with the NetApp products discussed in this document.