US 8,819,307 B1Granted

Identification and use of preferred path groups in host computer based on differential performance

AssigneeEMC Corporation

InventorsHelen S. Raizen, Michael E. Bappe, Vinay G. Rao, Subburaj Ramasamy, Jimmy K. Seto

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Abstract

A host computer accesses a federated storage volume at first and second frames (physical storage assemblies). The host identifies a preferred frame by (1) obtaining representative values of a performance metric for sets of paths to the volume, each set associated with a different frame, and (2) selecting the frame associated with the path set having the best representative value. In one example a response latency is used to detect different distances to the host and identify the closer frame, which will be preferred. Operating modes of the paths for non-preferred frames are set to “standby”. During subsequent operation using path selection to send storage operations to the volume, the host selects among paths in an “active” operating mode so as to access the volume at the preferred frame under normal operating condition. Standby paths are reserved for less normal operating conditions, such as when no active path is available.

Claims23

Dependent claims

A method of operating a host computer having access to a storage volume via two or more frames of a storage system, each frame being a uniquely identified manufactured assembly providing access to associated physical storage, comprising:

identifying one of the frames as a preferred frame by:
(1) obtaining representative values of a performance metric for respective sets of paths to the volume, each set of paths being associated with a respective different one of the frames;
and
(2) selecting as the preferred frame the frame associated with the set of paths having a best representative value of the performance metric, each frame that is not selected being a non-preferred frame;
for subsequent storage read and write operations in which path selection is used to send storage read and write operations to the volume via different paths, selecting from among paths associated with the preferred frame so as to access the volume under normal operating conditions at the preferred frame rather than at a non-preferred frame, the paths associated with the non-preferred frame being reserved for use under less normal operating conditions in which no active path is available or otherwise suitable for use;
wherein the two or more frames of the storage system include a first data storage array and a second data storage array;
wherein multiple first paths connect the host computer to the first data storage array;
wherein multiple second paths connect the host computer to the second data storage array;
wherein the performance metric is a latency measure;
wherein selecting, as the preferred frame, the frame associated with the set of paths having the best representative value of the performance metric includes:
choosing the first data storage array as the preferred frame over the second data storage array due to the first paths providing lower latency than the second paths, the second data storage array being a non-preferred frame;
wherein selecting from among the paths associated with the preferred frame includes:
after selecting the frame associated with the set of paths having the best representative value of the performance metric as the preferred frame, (i) selecting a single first path of the multiple first paths connecting the host computer to the first data storage array in response to an input/output command, and (ii) accessing the volume through the selected single first path to process the input/output command;
and
wherein an inter-frame communication link connects the first data storage array and the second data storage array together;
and wherein the method further comprises:
providing access to any content of the volume through only one of the first paths due to inter-frame access via the inter-frame communication link.

14 more elements

A computer operable as a host computer having access a storage volume via two or more frames of a storage system, each frame being a uniquely identified manufactured assembly providing access to associated physical storage, comprising:

processing circuitry;
memory;
input/output circuitry;
and
one or more data busses interconnecting the processing circuitry, memory and input/output circuitry,
wherein the memory is operative to store computer program instructions which, when executed by the processing circuitry, cause the computer to perform a method including:
identifying one of the frames as a preferred frame by:
(1) obtaining representative values of a performance metric for respective sets of paths to the volume, each set of paths being associated with a respective different one of the frames;
and
(2) selecting as the preferred frame the frame associated with the set of paths having a best representative value of the performance metric, each frame that is not selected being a non-preferred frame;
setting an operating mode of the paths associated with each non-preferred frame to a standby operating mode, and
for subsequent storage read and write operations in which path selection is used to send storage read and write operations to the volume via different paths, selecting from among paths in the active operating mode so as to access the volume under normal operating conditions at the preferred frame rather than at a non-preferred frame, the standby paths being reserved for use under less normal operating conditions in which no active path is available or otherwise suitable for use;
wherein the two or more frames of the storage system include a first data storage array and a second data storage array;
wherein multiple first paths connect the host computer to the first data storage array;
wherein multiple second paths connect the host computer to the second data storage array;
wherein the performance metric is a latency measure;
wherein selecting as the preferred frame the frame associated with the set of paths having the best representative value of the performance metric includes:
choosing the first data storage array as the preferred frame over the second data storage array due to the first paths providing lower latency than the second paths, the second data storage array being a non-preferred frame;
wherein selecting from among the paths in the active operating mode includes:
after choosing the first data storage array, (i) selecting a single path of the first paths connecting the host computer to the first data storage array in response to an input/output command, and (ii) accessing the volume through the selected single path to process the input/output command;
wherein an inter-frame communication link connects the first data storage array and the second data storage array together;
and
wherein the method further comprises:
providing access to any content of the volume through only one of the first paths due to inter-frame access via the inter-frame communication link.

21 more elements

A non-transitory computer readable storage medium storing computer program instructions which, when executed by a host computer having access to a storage volume via two or more data storage devices of a storage system, each data storage device being a uniquely identified manufactured assembly providing access to associated physical storage, cause the host computer to perform a method comprising:

identifying one of the data storage devices as a preferred data storage device by:
(1) obtaining representative values of a performance metric for respective sets of paths to the volume, each set of paths being associated with a respective different one of the data storage devices;
and
(2) selecting, as the preferred data storage device, the data storage device associated with the set of paths having a best representative value of the performance metric, each data storage device that is not selected being a non-preferred data storage device;
for subsequent storage read and write operations in which path selection is used to send storage read and write operations to the volume via different paths, selecting from among paths associated with the preferred data storage device so as to access the volume under normal operating conditions at the preferred frame rather than at a non-preferred data storage device, the paths associated with the non-preferred data storage device being reserved for use under less normal operating conditions in which no active path is available or otherwise suitable for use;
wherein the two or more data storage devices of the storage system include a first data storage device and a second data storage device;
wherein multiple first paths connect the host computer to the first data storage device;
wherein multiple second paths connect the host computer to the second data storage device;
wherein the performance metric is a latency measure;
wherein selecting, as the preferred data storage device, the data storage device associated with the set of paths having the best representative value of the performance metric includes:
choosing the first data storage device as the preferred data storage device over the second data storage device due to the first paths providing lower latency than the second paths, the second data storage device being a non-preferred frame;
wherein selecting from among the paths associated with the preferred frame includes:
after selecting the data storage device associated with the set of paths having the best representative value of the performance metric as the preferred frame, (i) selecting a single first path of the multiple first paths connecting the host computer to the first data storage device in response to an input/output command, and (ii) accessing the volume through the selected single first path to process the input/output command
wherein an inter-frame communication link connects the first data storage array and the second data storage array together;
and
wherein the method further comprises:
providing access to any content of the volume through only one of the first paths due to inter-frame access via the inter-frame communication link.

14 more elements

Dependencies are inferred from the claim text.

Facts

Application: 13/339,693Filed 29 Dec 2011
Granted: 26 Aug 2014
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

G06F 3/0635
Configuration or reconfiguration of storage systems: by changing the path, e.g. traffic rerouting, path reconfiguration
G06F 3/061
Specifically adapted to achieve a particular effect: improving I/O performance
G06F 3/067
Adopting a particular infrastructure: distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
H04L 45/12
Routing or path finding of packets in data switching networks: shortest path evaluation