RAID Controller Memory Reallocation During Rebuild
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current multi-device data storage systems, such as those using RAID techniques, face inefficiencies in resource reallocation during rebuild operations, leading to slowed data transfer rates and increased garbage collection requirements as storage devices approach maximum capacity.
Innovation Solution
The implementation of a RAID controller that maintains a stripe list to differentiate between valid and unused data sets, allowing for targeted reconstruction and reallocation of resources during rebuild operations, thereby reducing unnecessary reads and writes and optimizing memory space usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rebuild operation is performed to reconstruct data from a failed storage device to a new storage device, then data redundancy and reliability are restored, but data transfer rates slow down and garbage collection requirements increase as storage devices approach maximum capacity
Solution Approach 1:
The rebuild process is segmented into two distinct phases: (1) reconstructing only valid data sets from the failed device to the new device, and (2) clearing unused data sets from both the remaining devices and the new device. This segmentation allows the system to focus resources on essential data recovery while simultaneously preparing space for future writes, thereby maintaining higher data transfer rates during the rebuild operation.
Solution Approach 2:
The system performs preliminary identification of valid versus unused data sets before the actual rebuild begins. By using a stripe list to pre-categorize data sets, the system prepares the rebuild operation in advance, ensuring that only necessary data is transferred and space is pre-allocated for future use, reducing overall rebuild time and maintaining performance.
2Reliability
If all data sets are reconstructed during a rebuild operation, then complete data redundancy is achieved, but unnecessary reads and writes increase processing overhead
Solution Approach 1:
The invention extracts and processes only the necessary subset of data sets during rebuild operations. By using the stripe list to identify and separate valid data sets from unused data sets, the system extracts only the essential data that needs to be reconstructed, eliminating unnecessary reads and writes of already-unused data, thereby reducing overall rebuild time and processing overhead.
Solution Approach 2:
Instead of performing a complete reconstruction of all data sets, the system applies partial action by reconstructing only the valid data sets identified in the stripe list. This partial approach is sufficient to restore data redundancy while significantly reducing the time and resources required compared to a full reconstruction of all data sets including unused ones.
3Stability of the object's composition
If memory space is not reallocated during rebuild, then existing data structures are preserved, but garbage collection requirements increase and performance degrades
Solution Approach 1:
The rebuild process segments the treatment of different data sets: valid data sets are reconstructed to maintain data structure integrity, while unused data sets are cleared and reallocated. This segmentation allows the system to preserve necessary data structures while simultaneously optimizing space utilization and reducing garbage collection requirements, thereby maintaining high read/write access performance after rebuild.
Solution Approach 2:
The system changes the state parameter of unused data sets from 'allocated' to 'cleared' during the rebuild operation. By modifying this parameter for unused data sets while preserving valid data sets, the system optimizes memory space utilization and reduces the need for future garbage collection operations, improving overall system performance without compromising data structure integrity of active data.
Data Source
AI summary
Apparatus and method for managing data in a multi-device storage system, such as a RAID (redundant array of independent discs) system. Distributed data sets are stored across a plurality of storage devices. A selected storage device is replaced with a new storage device responsive to an anomalous event. A rebuild operation is performed to reconstruct data from the selected storage device to the new storage device. The rebuild process includes accessing a list of distributed data sets in a local memory. For each distributed data set in the list identified as constituting valid data, read commands are issued to the remaining storage devices and a write command is issued to the new storage device. For each distributed data set in the list identified as constituting unused data, a data clear command is issued to each of the remaining storage devices and to the new storage device.