Patent ID: 11971788
Assignee: EMC IP HOLDING COMPANY LLC
Field: Computer technology (Electrical engineering)
Classification: CPC G | IPC G

Claim 10:
11. A non-transitory storage medium having stored therein instructions that are executable by one or more hardware processors to perform operations comprising:
receiving, at an IO journal, a new entry that identifies a respective disk location L, and data X written at that disk location L;
determining whether a location specified in an oldest entry of the IO journal is specified in any other entries in the IO journal, and then:
when the location specified in the oldest entry is not specified in any other entries in the IO journal, adding the new entry to the IO journal, and augmenting the new entry with undo data; or
when the location specified in the oldest entry is specified in at least one other entry in the IO journal, setting data specified in the oldest entry as undo data for the next entry that identifies that location, and adding the new entry to the IO journal, wherein the undo data, when applied to a dataset, returns the dataset to a particular point in time; and
deleting the oldest entry from the IO journal,
wherein the IO journal is maintained at a fixed length, notwithstanding the adding and deleting of entries to the IO journal and the undo data is preserved without re-reading the undo data in the IO journal,
wherein the IO journal entries facilitate spinoff of a VM that is application-consistent at one or more particular points in time.