You can freely build on How IBM's Storage Controllers Keep Data Backups in the Right Order

What this patent covers

This patent describes a way for a storage controller to manage updates to data stored on a disk. When an application updates multiple records, the controller creates a circular queue to track these changes. Each update is linked to the previous one in a backward chain, and a counter keeps track of how many updates are pending. This allows a data mover to read the updates in the exact order they occurred, which is critical for sending them to a remote site for disaster recovery without data corruption.

What is now free to use

All 0 claims of US 5682513 are in the public domain. Specifically:

The 0 dependent claims add narrowing limitations and are also free.

What is NOT covered

Patent expiry frees this specific invention. Separately-patented improvements made after expiry may still be protected.

• Does not cover data storage systems that lack a cache-based circular queue structure.

• Does not cover methods of data transmission that do not require sequence-consistent ordering.

• Does not cover the specific hardware architecture of the host processor itself.

• Does not cover real-time data replication that occurs without a staging queue.

Who is building on this today

IBM remains a primary player in this space, particularly within their mainframe and enterprise storage divisions. Modern cloud providers like AWS, Azure, and Google Cloud have built upon these fundamental concepts of asynchronous replication to power their own block storage and database backup services.

Products built on expired version of this technology

How to cite this patent in your documentation

International Business Machines Corp. US Patent 5682513. Cache queue entry linking for DASD record updates. Granted 1997, expired 2015. Now in the public domain.

Note: This is a convenience citation. Consult a patent attorney for formal freedom-to-operate analysis.

PatentBrief is an educational resource and does not provide legal advice. Patent expiration information is derived from USPTO records and may not reflect continuation patents, divisional filings, or separately-patented improvements. For commercial use or production decisions, obtain a formal freedom-to-operate (FTO) opinion from a registered patent attorney.