Methods for using non-contiguously reserved storage space for data migration in a redundant hierarchic data storage system
US5542065A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 10, 1995 |
| Grant date | Jul 30, 1996 |
| Priority date | — |
| Expiry date | Feb 10, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F3/0673
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A hierarchic disk array data storage system has multiple storage disks that define a physical storage space and a RAID management system that maps the physical storage space into two virtual storage spaces. A RAID-level virtual storage space presents the physical storage space as mirror and parity RAID areas where the mirror RAID areas store data according to RAID Level 1 and the parity RAID areas store data according to RAID Level 5. An application-level virtual storage space presents the physical storage space as multiple virtual blocks. The RAID management system migrates data between the mirror and parity RAID areas to optimize performance and reliability. To facilitate migration, the RAID management system guarantees a minimum of unused storage space that can be used to empty a RAID area for the purpose of converting the RAID level or other storage attribute of the RAID area. The minimum unused storage space is preferably equivalent in size to at least one largest parity RAID area. However, the unused storage space is not in any one physical location, but can be allowed to distribute itself over various RAID areas in a non-contiguous manner across the storage disks.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.