Silicon Graphics International Corporation

Kevan Flint Rehm

Joseph Carl Nemeth

Judith Ann Schmitz

John Michael Sygulla

Benjamin Paul Myers

The present invention relates to a temporal base method of mutual exclusion control of a shared resource. The invention will usually be implemented by a plurality of host computers sharing a shared resource where each host computer will read a reservation memory that is associated with the shared resource. Typically a first host computer will perform and initial read of the reservation memory and when the reservation memory indicates that the shared resource is available, the first host computer will write to the reservation memory. After a time delay, the host computer will read the reservation memory again to determine whether it has won access to the resource. The first host computer may determine that it has won access to the shared resource by checking that data in the reservation memory includes an identifier corresponding to the first host computer.

Temporal based collaborative mutual exclusion control of a shared resource

A two part process is used for modifying records to be written and retrieved from tape devices. A record is appended with a cyclic redundancy check and a string of zeros. Submitting the entire record to tape drives which are logical block protection enabled will result in no change. For drives that are not LBP enabled, the string of zeros at the end of the record is removed. In addition to determining whether a drive is LBP compliant, a determination may be made as to whether a drive is a linear tape open drive from a particular manufacturer. Linear tape open drives may behave similarly as drives which may not be enabled with logical block protection.

Logical block protection for tape interchange

Quotas are tracked for user usage of hard disk drive space and offline backup storage space. The quota is enforced against the total space utilized by a user, not just high tier hard drive space usage. When data is migrated from hard disk drive space to backup storage space, data metadata is updated to reflect data kept offline for the user. As such, when users request to store new data, the data usage of hard disk space and backup storage space is determined from the metadata that reflects both data types, and the total storage spaced for the user is used to grant or reject the user's request to store more data in the system.

Total quotas for data storage system

Tape device paths, library slots and drive information are automatically collected by agents at nodes in a library cluster. The information is reported to a central server database. The central server accesses the information and maps tape devices to path information so an administrator may easily have access to configuration information for the tape device cluster. When a tape device cluster is updated, for example through changes to a device, an added device, device failure or some other reason, the change is detected and the cluster configuration is automatically updated.

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Brooklyn Park, MN, United States of America

Kevan Flint Rehm