Performing input-output multi-pathing from user space
An apparatus comprises a host device configured to communicate over a network with a storage system comprising a plurality of storage devices. The host device is configured to implement a multi-path input-output driver for delivery of input-output operations from the host device to the storage system over the network. The multi-path input-output driver is configured to perform, in user space of the host device, discovery of paths to logical storage volumes of the storage system, to identify two or more of the paths providing connection to a given one of the logical storage volumes, to generate, in the user space of the host device, a given multi-path logical device grouping the identified two or more paths providing connection to the given logical storage volume, and to submit input-output operations directed to the given logical storage volume via the given multi-path logical device in the user space of the host device.
1. An apparatus comprising:
a host device configured to communicate over a network with a storage system comprising a plurality of storage devices;
the host device comprising a processor coupled to a memory configured to implement a multi-path input-output driver for delivery of input-output operations from the host device to the storage system over the network, the host device comprising a kernel space and a user space;
wherein the multi-path input-output driver is configured:
to perform, in the user space of the host device, discovery of a plurality of paths to one or more logical storage volumes of the storage system;
to identify two or more of the plurality of paths providing connection to a given one of the one or more logical storage volumes;
to generate, in the user space of the host device, a given multi-path logical device grouping the identified two or more paths providing connection to the given logical storage volume; and
to submit input-output operations directed to the given logical storage volume via the given multi-path logical device in the user space of the host device, wherein submitting the input-output operations directed to the given logical storage volume via the multi-path logical device in the user space of the host device bypasses copying of data for the submitted input-output operations from the user space of the host device to the kernel space of the host device.
2. The apparatus of claim 1 further comprising one or more additional host devices each configured to communicate over the network with the storage system and wherein each additional host device comprises a multi-path input-output driver configured to control delivery of input-output operations from that host device to the storage system over selected ones of a plurality of paths through the network.
3. The apparatus of claim 1 wherein the storage devices comprise respective ones of the one or more logical storage volumes of the storage system.
4. The apparatus of claim 1 wherein performing the discovery of the plurality of paths comprises utilizing user space host interfaces to establish connection between the host device and a front end of a storage array of the storage system hosting the one or more logical storage volumes.
5. The apparatus of claim 1 wherein identifying the two or more paths providing connection to the given logical storage volume comprises:
sending a command over each of the plurality of paths for a unique identifier of its associated logical storage volume; and
identifying ones of the paths returning a given unique identifier associated with the given logical storage volume as the two or more paths providing connection to the given logical storage volume.
6. The apparatus of claim 5 wherein the given unique identifier associated with the given logical storage volume comprises a Namespace Globally Unique Identifier (NGUID) for the given logical storage volume.
7. The apparatus of claim 1 wherein generating the given multi-path logical device grouping the identified two or more paths providing connection to the given logical storage volume comprises:
forming, in a block device layer in the user space of the host device, a block device for each of the identified two or more paths providing connection to the given logical storage volume, the block device layer providing an application programming interface for implementing the block devices to interface with the given logical storage volume; and
creating a given multi-path pseudodevice as a collection of the block devices for each of the identified two or more paths providing connection to the given logical storage volume.
8. The apparatus of claim 7 wherein the given multi-path pseudodevice comprises a data structure specifying:
a multi-path identifier for the given multi-path pseudodevice;
a unique identifier of the given logical storage volume; and
identifiers of the block devices formed for each of the identified two or more paths providing connection to the given logical storage volume.
9. The apparatus of claim 1 wherein the given multi-path logical device provides multi-pathing functionality for applications running in the user space of the host device independent of a transport protocol utilized by the identified two or more paths providing connection to the given logical storage volume.
10. The apparatus of claim 1 wherein submitting the input-output operations directed to the given logical storage volume via the given multi-path logical device in the user space of the host device comprises bypassing the kernel space of the host device.
11. The apparatus of claim 10 wherein bypassing the kernel space of the host device comprises providing the data of the submitted input-output operations directly to the storage system over at least one of the identified two or more paths providing connection to the given logical storage volume via at least one of the plurality of communication adapters.
12. The apparatus of claim 1 wherein the host device is further configured:
to identify two or more of the plurality of paths providing connection to an additional one of the one or more logical storage volumes;
to generate, in the user space of the host device, an additional multi-path logical device grouping the identified two or more paths providing connection to the additional logical storage volume; and
to submit input-output operations directed to the given logical storage volume via the additional multi-path logical device in the user space of the host device.
13. The apparatus of claim 1 wherein submitting the input-output operations directed to the given logical storage volume via the given multi-path logical device in the user space of the host device comprises utilizing the given multi-path logical device to provide load balancing across the identified two or more paths providing connection to the given logical storage volume.
14. The apparatus of claim 1 wherein submitting the input-output operations directed to the given logical storage volume via the given multi-path logical device in the user space of the host device comprises utilizing the given multi-path logical device to provide input-output failover by re-routing a given input-output operation from a failed one of the identified two or more paths providing connection to the given logical storage volume to an alive one of the identified two or more paths providing connection to the given logical storage volume.
15. A method comprising:
performing, by a multi-path input-output driver implemented by a host device configured to communicate over a network with a storage system comprising a plurality of storage devices, discovery of a plurality of paths to one or more logical storage volumes of the storage system, the host device comprising a kernel space and a user space;
identifying, by the multi-path input-output driver, two or more of the plurality of paths providing connection to a given one of the one or more logical storage volumes;
generating, by the multi-path input-output driver in the user space of the host device, a given multi-path logical device grouping the identified two or more paths providing connection to the given logical storage volume; and
submitting, by the multi-path input-output driver, input-output operations directed to the given logical storage volume via the given multi-path logical device in the user space of the host device, wherein submitting the input-output operations directed to the given logical storage volume via the multi-path logical device in the user space of the host device bypasses copying of data for the submitted input-output operations from the user space of the host device to the kernel space of the host device.
16. The method of claim 15 wherein generating the given multi-path logical device grouping the identified two or more paths providing connection to the given logical storage volume comprises:
forming, in a block device layer in the user space of the host device, a block device for each of the identified two or more paths providing connection to the given logical storage volume, the block device layer providing an application programming interface for implementing the block devices to interface with the given logical storage volume; and
creating a given multi-path pseudodevice as a collection of the block devices for each of the identified two or more paths providing connection to the given logical storage volume.
17. The method of claim 16 wherein the given multi-path pseudodevice comprises a data structure specifying:
a multi-path identifier for the given multi-path pseudodevice;
a unique identifier of the given logical storage volume; and
identifiers of the block devices formed for each of the identified two or more paths providing connection to the given logical storage volume.
18. A computer program product comprising a non-transitory processor-readable storage medium having stored therein program code of one or more software programs, wherein the program code, when executed by a multi-path input-output driver implemented by a host device configured to communicate over a network with a storage system comprising a plurality of storage devices, causes the multi-path input-output driver:
to perform, in a user space of the host device, discovery of a plurality of paths to one or more logical storage volumes of the storage system, the host device comprising a kernel space and the user space;
to identify two or more of the plurality of paths providing connection to a given one of the one or more logical storage volumes;
to generate, in the user space of the host device, a given multi-path logical device grouping the identified two or more paths providing connection to the given logical storage volume; and
to submit input-output operations directed to the given logical storage volume via the given multi-path logical device in the user space of the host device, wherein submitting the input-output operations directed to the given logical storage volume via the multi-path logical device in the user space of the host device bypasses copying of data for the submitted input-output operations from the user space of the host device to the kernel space of the host device.
19. The computer program product of claim 18 wherein generating the given multi-path logical device grouping the identified two or more paths providing connection to the given logical storage volume comprises:
forming, in a block device layer in the user space of the host device, a block device for each of the identified two or more paths providing connection to the given logical storage volume, the block device layer providing an application programming interface for implementing the block devices to interface with the given logical storage volume; and
creating a given multi-path pseudodevice as a collection of the block devices for each of the identified two or more paths providing connection to the given logical storage volume.
20. The computer program product of claim 19 wherein the given multi-path pseudodevice comprises a data structure specifying:
a multi-path identifier for the given multi-path pseudodevice;
a unique identifier of the given logical storage volume; and
identifiers of the block devices formed for each of the identified two or more paths providing connection to the given logical storage volume.