SAN Switch Multi-Pass Erase Bypassing Caching
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Solution Overview
Problem
Conventional data deletion methods in storage area networks are inadequate as they fail to completely remove data remnants, even after encryption, due to data remanence, and are often intrusive, expensive, or limited to specific environments.
Innovation Solution
A multi-pass erase method using a storage area network switch with virtual initiators that repeatedly writes specific bit patterns over data blocks, bypassing caching mechanisms and accounting for encoding schemes, to ensure complete data removal without leaving residual representations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If simple erase is performed on storage arrays, then data deletion is fast and easy, but data remanence remains and reconstruction is possible
Solution Approach 1:
The patent implements multi-pass erase operations where data is overwritten multiple times in sequence. Each pass writes different patterns (zeros, ones, random data) over the original data blocks, progressively destroying remanence. This periodic rewriting action ensures complete data removal while maintaining operational simplicity through automated multi-pass execution.
Solution Approach 2:
The system performs preliminary identification of data blocks before erasure, using metadata, file tables, and directory structures to locate and mark blocks for erasure. This preliminary action enables the multi-pass erase to target only relevant data blocks efficiently, maintaining simplicity while ensuring complete removal of removable data.
2Reliability
If encryption is applied to data, then data security is improved, but plaintext data remains vulnerable and can be reconstructed
Solution Approach 1:
The system performs preliminary identification and isolation of encrypted data blocks before erasure. By using encryption metadata, file tables, and directory structures, the system locates encrypted data blocks and prepares them for multi-pass erasure. This preliminary action ensures that both encrypted and plaintext data are properly identified and erased, preventing any form of data reconstruction.
Solution Approach 2:
The multi-pass erase process repeatedly overwrites encrypted data blocks with different patterns (zeros, ones, random data) multiple times. This periodic action progressively destroys any potential remanence of plaintext data beneath encrypted layers, ensuring complete data removal while maintaining security.
3Reliability
If multi-pass erase is performed, then data removal completeness is improved, but operation time and complexity increase
Solution Approach 1:
The system performs preliminary identification of data blocks using metadata, file tables, and directory structures before initiating erasure. This preliminary action creates an efficient map of blocks to be erased, enabling the multi-pass process to target only relevant blocks rather than scanning entire storage arrays, thus reducing overall operation time while maintaining completeness.
Solution Approach 2:
The multi-pass erase operation applies different strategies to different data blocks based on their characteristics. The system identifies and erases only removable data blocks (those with valid metadata references) rather than attempting to erase all blocks. This localized approach optimizes operation time by focusing resources only where data removal is possible and necessary.
4Ease of operation
If conventional erase mechanisms are used, then ease of operation is maintained, but data remanence remains and reconstruction is possible
Solution Approach 1:
The system implements automated multi-pass erase operations that repeatedly overwrite data blocks with different patterns. This periodic action progressively destroys data remanence while maintaining ease of operation through automated execution. The system handles the complexity of multi-pass operations transparently, presenting users with simple erase commands while performing thorough removal in the background.
Solution Approach 2:
The SAN switch performs multi-pass erase operations autonomously without requiring manual intervention or complex user configuration. The system automatically identifies data blocks, executes multiple overwrite passes, and verifies completion, making the process self-service oriented. This maintains ease of operation while effectively eliminating data remanence through automated thorough erasure.
Data Source
AI summary
Techniques are provided for performing multi-pass erase. An erase command is received at a storage area network (SAN) switch in a storage area network. The erase command is associated with a block of data on a target device. A virtual initiator is determined for performing the erase command on the block of data. Multiple bit patterns are generated using a multi-pass erase algorithm. The multiple bit patterns are generated for writing over the block of data on the target device. Repeated writes are performed over the block of data using the bit patterns. The block of data is repeatedly overwritten to remove remanence of the block of data on the target device.