公开(公告)号：WO2013040052A3

公开(公告)日：2013-03-21

申请号：PCT/US2012/054887

申请日：2012-09-12

Applicant: MICROSOFT CORPORATION

Inventor： MEHRA, Karan ,  VERMA, Surendra ,  DIETRICK, John R.

IPC: G06F12/00 ,  G06F3/06

Abstract: Upon receiving a request to allocate a storage region, a storage device may initialize the contents of the storage device to default values ( e.g. , zero) in order to avoid problems arising from unknown data stored in the locations of the storage region ( e.g. , upon writing a data set to a location involved in a mirroring relationship, uninitialized data in the corresponding mirror location may result in a mismatch that jeopardizes the written data). However, initializing the storage device may be time-consuming and inefficient. Instead, a usage bitmap may be generated that, for respective location sets of the storage region, indicates whether values exist in the location. A read request may be fulfilled by examining the usage bitmap to determine whether values exist in the specified location, and if not, the default value may be returned without accessing the storage device. Other efficiencies may also be achieved using the usage bitmap.

公开(公告)号：EP2756402A2

公开(公告)日：2014-07-23

申请号：EP12830948.1

申请日：2012-09-12

Applicant: Microsoft Corporation

Inventor： MEHRA, Karan ,  VERMA, Surendra ,  DIETRICK, John R.

IPC: G06F12/00 ,  G06F3/06

CPC classification number: G11B20/1217 ,  G06F3/0611 ,  G06F3/0652 ,  G06F3/0673

Abstract: Upon receiving a request to allocate a storage region, a storage device may initialize the contents of the storage device to default values (
e.g. , zero) in order to avoid problems arising from unknown data stored in the locations of the storage region (
e.g. , upon writing a data set to a location involved in a mirroring relationship, uninitialized data in the corresponding mirror location may result in a mismatch that jeopardizes the written data). However, initializing the storage device may be time-consuming and inefficient. Instead, a usage bitmap may be generated that, for respective location sets of the storage region, indicates whether values exist in the location. A read request may be fulfilled by examining the usage bitmap to determine whether values exist in the specified location, and if not, the default value may be returned without accessing the storage device. Other efficiencies may also be achieved using the usage bitmap.