Remote data facility prefetch
AssigneeEMC Corporation
InventorsRobert S. Mason, Jr., Yuval Ofek, Dan Arnon
Life of this patent
Estimating the term…
Abstract
A mechanism for optimizing predictive read performance in a data storage system that is connected to a geographically remote data storage system by a data link for remote replication of data in support of data recovery operations. The data storage system initiates a local prefetch and initiates via the data link a remote prefetch by the remote data storage system to retrieve data from storage devices coupled to the local and remote data storage systems, respectively. The remote prefetch read start address is offset from the local prefetch read start address by a programmable track offset value. The programmable track offset value is adjusted to tune the prefetch workload balance between the local and remote data storage systems.
Claims16
A method for performing a prefetch operation on data being maintained by a data storage system and a remote data storage system arranged in a mirrored configuration and interconnected by a data link, comprising:
- initiating a local prefetch operation directed to data on a local mirrored copy of the data storage system;
- sending a read command to the remote data storage system over the data link, the read command causing the remote data storage system to provide other data prefetched from a remote mirrored copy of the remote data storage system to the data storage system over the data link;
- and
- wherein the local prefetch operation begins at a first address of a first track number in a range of consecutive prefetch addresses and the read command is directed to a second address of a second track number in the range of consecutive prefetch addresses, the second track number being offset from the first track number by a programmable track offset value.
A method for performing a prefetch operation on data being maintained by a data storage system and a remote data storage system arranged in a mirrored configuration and interconnected by a data link, comprising:
- initiating a local prefetch operation directed to data on a local mirrored copy of the data storage system;
- sending a read command to the remote data storage system over the data link, the read command causing the remote data storage system to provide other data prefetched from a remote mirrored copy of the remote data storage system to the data storage system over the data link;
- and
- wherein the data storage system includes a cache memory for storing data and a cache directory for storing metadata, the metadata including a prefetch flag for indicating that data was retrieved by the local prefetch operation and a remote prefetch flag for indicating that data was retrieved by the remote prefetch operation.
A storage controller for performing a prefetch operation directed to data stored on a storage device comprising:
- a data link;
- an interface for coupling the storage controller to a remote data storage system on the data link for mirroring the stored data, the interface requesting assistance from the remote data storage system in performing the prefetch operation;
- a device interface coupled to the storage device, the device interface initiating a local prefetch operation directed to the stored data, the device interface causing the interface to send a read command to the remote data storage system over the data link, the read command causing the remote data storage system to provide other data prefetched from a remote mirrored copy in the remote data storage system to the device interface over the data link;
- and
- wherein the prefetch operation at the storage controller begins at a first address of a first track number in a range of consecutive prefetch addresses and the read command is directed to a second address of a second track number in the range of consecutive prefetch addresses, the second address being offset from the first address by a programmable offset value.
A storage controller for performing a prefetch operation directed to data stored on a storage device comprising:
- a data link;
- an interface for coupling the storage controller to a remote data storage system on the data link for mirroring the stored data, the interface requesting assistance from the remote data storage system in performing the prefetch operation;
- a device interface coupled to the storage device, the device interface initiating a local prefetch operation directed to the stored data, the device interface causing the interface to send a read command to the remote data storage system over the data link, the read command causing the remote data storage system to provide other data prefetched from a remote mirrored copy in the remote data storage system to the device interface over the data link, the read command further causing the remote data storage system to initiate a remote prefetch operation directed to a corresponding remote mirrored copy on the remote data storage system;
- a cache memory for storing data;
- and
- a cache directory for storing metadata associated with the stored data, the metadata including a prefetch flag for indicating that the stored data was retrieved by the local prefetch operation and a remote prefetch flag for indicating that stored data was retrieved by the remote prefetch operation.
Dependencies are inferred from the claim text.