Abstract: A method and system for synchronizing a plurality of data images in a computer system, includes a primary image and at least one secondary image which are synchronized. A host computer issues write requests to a primary image site which is also transmitted to a secondary image site. Writing to the primary image and the secondary image at the primary image site and secondary site is conducted simultaneously. If a failure to write to the secondary image occurs, a fracture log is created which is a bitmap representative of changed regions in the primary image at the primary image site in response to the write request. When writing to the secondary image is restored, the log can be used to synchronize the primary image and the secondary image.

Abstract: A method and system for managing I/O resources for communications between a host and a target device through at least one adapter, involves setting a local resource associated with each adapter. If a target device cannot accept an I/O request, the local resource associated with each adapter is set to the number of I/O resources currently used by each adapter associated therewith. The host is configured to issue no more than the local resource number of I/O requests to any individual adapter. The local resources may be periodically rebalanced to account for changes in system needs.