Method for preventing overwriting cache buffer transaction entries until corresponding log buffer entries have been copied to log partition of the disk
AssigneeTexas Instruments Incorporated
InventorsHoward R. Courts, George B. Keith
Life of this patent
Estimating the term…
Abstract
A method for logging transactions which alters a file system stored on a secondary storage device is disclosed. The method includes the steps of writing data to a buffer in a buffer cache and logging the transaction in a log buffer residing on a primary storage device. A flag is set for the modified buffer, which is then added to a list of modified buffers. As the log buffer becomes substantially full, its contents are copied to a log partition residing on the secondary storage device. After an abnormal system shutdown, the contents of the log partition are copied to the buffer cache in order to restore the disk filing system.
Claims13
A method for logging a plurality of transactions performed on a file system stored in a mass storage device of a computer system, said computer system utilizing a buffer cache for storing transaction entries, each of said transaction entries comprises a header with a Don't.sub.-- Write.sub.-- Yet flag and a modified flag, the method comprising the steps of:
- accessing said buffer cache for performing a transaction of one of said transactions;
- logging said transaction entry in a log buffer of said computer system;
- setting said Don't.sub.-- Write.sub.-- Yet flag and said modified flag of said transaction entry in said buffer cache for indicating the existence of said logged entry in the log buffer thereby preventing the overwriting of said transaction entry in said buffer cache;
- copying said log buffer entry to said log partition on said mass storage device;
- and
- resetting said Don't.sub.-- Write.sub.-- Yet flag and said modified flag of all corresponding cache buffers.
Dependencies are inferred from the claim text.