Virtual Disk Storage Allocation Across Multiple Datastores
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Solution Overview
Problem
In virtualized computing environments, virtual machines often face storage allocation challenges, particularly when thinly provisioned virtual disks require additional space, as the underlying datastores may run out of free space, leading to potential failures or 'hung' states, especially when all extents are fully allocated and no additional storage can be allocated.
Innovation Solution
A method is implemented to dynamically allocate additional storage for virtual disks from other datastores when the initial datastore lacks sufficient free space, allowing the virtual machine to access the storage as a single virtual disk, thereby ensuring continuous operation by utilizing available space from multiple datastores.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If thin provisioning is used to dynamically allocate storage, then storage efficiency is improved, but the risk of storage availability failure increases when the datastore runs out of space
Solution Approach 1:
The patent transitions from a single-dimension storage allocation (one datastore per virtual disk) to a multi-dimensional approach by allowing virtual disks to be allocated from multiple different datastores. When the initial datastore exhausts its space, the system can allocate additional storage from alternative datastores, effectively adding spatial diversity to the storage allocation dimension and preventing storage availability failures while maintaining thin provisioning efficiency.
2Ease of operation
If storage space is allocated from a single datastore, then management simplicity is maintained, but storage capacity flexibility is reduced when the datastore becomes full
Solution Approach 1:
The patent makes the storage allocation system multi-functional by enabling virtual disks to draw storage capacity from multiple different datastores rather than being confined to a single source. This universality allows the system to adapt to varying storage conditions across different datastores, providing capacity flexibility when one datastore becomes full while the management system maintains simplified oversight through automated allocation logic.
3Quantity of substance
If extend or extent operations are used to allocate additional storage, then storage capacity can be increased, but the operations are precluded when all extents are fully allocated
Solution Approach 1:
The patent introduces a intermediary storage allocation mechanism that acts as a mediator between the virtual machine's storage needs and the physical datastore extents. When traditional extend or extent operations are precluded due to fully allocated extents, this intermediary system identifies and allocates storage from alternative datastores with available capacity, thereby bypassing the limitation of exhausted extents while maintaining storage capacity expansion capability.
Data Source
AI summary
A management server allocates storage for a virtual disk of a virtual machine configured to execute on a first host computer, where the first host computer is associated with a plurality of data storage devices including first and second data storage devices, and where a first portion of storage is allocated to the virtual disk from the first storage device. The management server receives a request to allocate a second portion of storage to the virtual disk of the virtual machine and, responsive to determining that the first data storage device has insufficient free storage space from which to allocate the second portion of storage, selects the second data storage device having sufficient free storage space from which to allocate the second portion of storage. The management server allocates the second portion of storage for the virtual disk of the virtual machine from the second data storage device, wherein the virtual machine accesses the first and second portions of storage as a single virtual disk.