Tape Emulation Storage Reclamation via Segmentation
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Solution Overview
Problem
In modern tape systems using storage emulations, space cannot be effectively reclaimed for expired data/files since entire tape images must be maintained if any unexpired data exists, preventing the reuse of storage space.
Innovation Solution
Determining expired portions of a tape image, overwriting them with a uniform value, and employing compression or deduplication to reclaim storage space, with expiration information provided by header information and managed by both host computers and tape emulation units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If entire tape images are maintained on storage systems, then data integrity and reliability are preserved, but storage space cannot be reclaimed for expired files
Solution Approach 1:
The patent divides a tape image into multiple segments or portions, allowing individual portions to be managed separately. This enables expired portions to be identified and reclaimed independently while preserving unexpired portions, thus resolving the contradiction between maintaining data integrity and reclaiming storage space.
Solution Approach 2:
The patent applies different quality or status attributes to different portions of the tape image based on their expiration status. Expired portions are marked for reclamation while unexpired portions maintain their protective status, allowing selective space reclamation without compromising overall data integrity.
2Ease of operation
If tape images are stored as single files on storage systems, then simplified storage management is achieved, but granular space reclamation for expired data becomes impossible
Solution Approach 1:
The patent introduces segmentation of tape images into manageable portions while maintaining the single-file storage structure. This allows the system to track and manage expiration status at the portion level without requiring complex multi-file structures, thus preserving ease of operation while enabling granular space reclamation.
3Loss of substance
If physical deletion of expired files is implemented, then storage space can be reclaimed, but data integrity and security may be compromised
Solution Approach 1:
The patent implements a controlled discarding and recovering process where expired portions are identified, marked, and reclaimed through systematic procedures. This ensures that only truly expired data is removed while maintaining security protocols and data integrity for remaining portions.
4Loss of substance
If copying tapes with small percentages of unexpired files to new tapes is used, then space reclamation is achieved, but additional storage operations and time are required
Solution Approach 1:
The patent extracts and identifies expired portions within tape images and directly reclaims the storage space occupied by these portions. This eliminates the need for time-consuming copy operations by directly removing expired data and making space available for reuse.
Data Source
AI summary
Reclaiming storage space in a tape emulation unit includes determining portions of a tape image of the tape emulation unit that correspond to data/files that have expired, for each of the portions that have expired, overwriting each of the portions with a same value, and the tape emulation unit performing at least one of: compression or deduplication on each of the portions to reclaim storage space maintained by each of the portions. The same value may be zeros. Expiration information may be provided by header information on the tape image. The expiration information may be written by a host computer coupled to the tape emulation unit. The host computer may determine portions that have expired based on the header information. The host computer may run tape management software. The tape emulation unit may determine portions that have expired based on the header information.