Object storage

Object storage is a type of distributed storage that stores data and metadata in objects and containers instead of storing data in blocks as in traditional storage.


OpenStack is an open source operating system for private and public clouds. OpenStack includes multiple required and optional components that cloud administrators can mix and match according to the requirements of the cloud. All OpenStack components are deployed as services.


A subscription to the Mirantis-managed service provided on Mirantis Cloud Platform. When customers manage MCP themselves, they can choose ProdCare (24x7) or LabCare (8x5) subscriptions.

OpenStack Block Storage service

See Cinder

Overcommit ratio

The overcommit ratio defines the amount of virtual CPU, memory, and disk resources that can be allocated to instances on a compute node, relative to the amount of physical resources available on that node. Often, instances do not fully utilize all resources allocated to them. Overcommittment allows you to better utilize the available resources in light of this fact. You must carefully monitor resource utilization to ensure that adequate resources are available on the system. If this ratio is set too high for your workload, customers may suffer performance degradation for the instances. If CPU and memory resources are exhausted, instances may be destroyed. If a host runs out of disk space, instances may suffer spurious disk I/O errors.

Overcommit ratios can be set for CPUs, RAM, and disk. By default, Fuel sets the overcommit ratio for CPUs at 8:1; This means that, if your physical node has 12 cores, the Filter Scheduler sees 96 available virtual cores and so could provision 24 4-core instances on that physical node.

Fuel sets the overcommit ratio for CPUs at 8:1, and RAM and disks at 1:1, meaning that the scheduler only sees the actual amount of physical memory and physical disk space that is allocated. OpenStack sets the overcommit ratio for CPUs at 16:1 and the overcommit ratio for RAM at 1.5:1. The default CPU overcommit rate of 8:1 is necessary for the Mirantis CI tools but may not be the best default rate for customer environments. If you do not know what your VM workload is going to be, reset this ratio to 1:1 to avoid CPU congestion. You can then use the atop service and other tools to monitor activity in your environment to determine whether a different overcommit ratio is appropriate for your environment.