Patent Application
20210157487
This disclosure relates to computing systems and related devices and methods, and, more particularly, to a storage system having storage engines and disk arrays interconnected by redundant fabrics to enable inter-processor messaging, atomic accessibility to metadata, inter-node data movement, and NVMeoF shared access to solid state drives.
The following Summary and the Abstract set forth at the end of this application are provided herein to introduce some concepts discussed in the Detailed Description below. The Summary and Abstract sections are not comprehensive and are not intended to delineate the scope of protectable subject matter, which is set forth by the claims presented below.
All examples and features mentioned below can be combined in any technically possible way.
In some embodiments, a storage system includes a plurality of storage engines, each storage engine having two compute nodes, and a plurality of disk arrays. Two redundant fabrics interconnect each of the compute nodes with each of the disk arrays. The fabric enables simultaneous inter-node reliable messaging and the ability to atomically read, atomically write, and perform complex atomic operations on metadata contained in memory on any node of the storage system. The fabric also enables the ability to copy small to large blocks of data to and from a node's local memory from and to any other compute node's memory. The NVMeoF protocol is used to access, simultaneously from any node, to or from any solid-state drive in the storage system.
In some embodiments, the data movement elements are provided with hardware assisted end-to-end data consistency protection in the form of DIF, that ensures that data stored in volatile and non-volatile elements is checked for consistency every time it is accessed and moved from location to location within the storage system. Together, these features allow one fabric to provide all the system intercommunication services, as well as accelerate in time and reduce processor workload to SSD data, faster access to and manipulation of system metadata, and faster access to and manipulation of data cached within the storage system.
In some embodiments, to support high availability, two fabrics are used simultaneously active-active with all end-point interfaces dual-ported, one port to each of the individual fabrics. This combination of features lowers system cost and reduces cabling complexity with one form of fabric, and because the amount of work to do a task is reduced, allows a system to deliver the same performance at reduced cost or gives increased performance at the same cost.
Aspects of the inventive concepts will be described as being implemented in a storage system 100 connected to a host computer 102. Such implementations should not be viewed as limiting. Those of ordinary skill in the art will recognize that there are a wide variety of implementations of the inventive concepts in view of the teachings of the present disclosure.
Some aspects, features and implementations described herein may include machines such as computers, electronic components, optical components, and processes such as computer-implemented procedures and steps. It will be apparent to those of ordinary skill in the art that the computer-implemented procedures and steps may be stored as computer-executable instructions on a non-transitory tangible computer-readable medium. Furthermore, it will be understood by those of ordinary skill in the art that the computer-executable instructions may be executed on a variety of tangible processor devices, i.e., physical hardware. For ease of exposition, not every step, device or component that may be part of a computer or data storage system is described herein. Those of ordinary skill in the art will recognize such steps, devices and components in view of the teachings of the present disclosure and the knowledge generally available to those of ordinary skill in the art. The corresponding machines and processes are therefore enabled and within the scope of the disclosure.
The terminology used in this disclosure is intended to be interpreted broadly within the limits of subject matter eligibility. The terms “logical” and “virtual” are used to refer to features that are abstractions of other features, e.g. and without limitation, abstractions of tangible features. The term “physical” is used to refer to tangible features, including but not limited to electronic hardware. For example, multiple virtual computing devices could operate simultaneously on one physical computing device. The term “logic” is used to refer to special purpose physical circuit elements, firmware, software, computer instructions that are stored on a non-transitory tangible computer-readable medium and implemented by multi-purpose tangible processors, and any combinations thereof.
The storage system 100 includes a plurality of compute nodes 1161-1164, possibly including but not limited to storage servers and specially designed compute engines or storage directors for providing data storage services. In some embodiments, pairs of the compute nodes, e.g. (1161-1162) and (1163-1164), are organized as storage engines 1181 and 1182, respectively, for purposes of facilitating failover between compute nodes 116. In some embodiments, the paired compute nodes 116 of each storage engine 118 are directly interconnected by communication links 120. As used herein, the term “storage engine” will refer to a storage engine, such as storage engines 1181 and 1182, which has a pair of (two independent) compute nodes, e.g. (1161-1162) or (1163-1164). A given storage engine 118 is implemented using a single physical enclosure and provides a logical separation between itself and other storage engines 118 of the storage system 100. A given storage system 100 may include one or multiple storage engines 118.
Each compute node, 1161, 1162, 1163, 1164, includes processors 122 and a local volatile memory 124. The processors 122 may include a plurality of multi-core processors of one or more types, e.g. including multiple CPUs, GPUs, and combinations thereof. The local volatile memory 124 may include, for example and without limitation, any type of RAM. Each compute node 116 may also include one or more FEs (front end adapters) 126 for communicating with the host computer 102.
Each compute node 1161-1164 may also include one or more fabric access module 128. Fabric access module 128 enables the compute nodes 1161-1164 to communicate with each other over fabric 136, and also enables the compute nodes 1161-1164 to communicate with disk arrays 1301-1304 over fabric 136, thereby enabling access to managed drives 132. An example interconnecting fabric may be implemented using InfiniBand.
In some embodiments, managed drives 132 are storage resources dedicated to providing data storage to storage system 100 or are shared between a set of storage systems 100. Managed drives 132 may be implemented using numerous types of memory technologies for example and without limitation any of the SSDs and HDDs mentioned above. In some embodiments the managed drives 132 are implemented using Non-Volatile Memory (NVM) media technologies, such as NAND-based flash, or higher-performing Storage Class Memory (SCM) media technologies such as 3D XPoint and Resistive RAM (ReRAM). In some embodiments, each drive is a dual ported NVMe drive, with each port connected to an NVMe over Fabric interface that is itself connected to each fabric. The drive ports and fabric are all 100% active-active and fully redundant.
Each compute node 116 may allocate a portion or partition of its respective local volatile memory 124 to a virtual shared “global” memory 138 that can be accessed by other compute nodes 116, e.g. via Direct Memory Access (DMA) or Remote Direct Memory Access (RDMA). In some embodiments, compute nodes 116 can also implement atomic operations on their own memory or on the memory of any other compute node 116.
The storage system 100 maintains data for the host applications 104 running on the host computer 102. For example, host application 104 may write host application data to the storage system 100 and read host application data from the storage system 100 in order to perform various functions. Examples of host applications 104 may include but are not limited to file servers, email servers, block servers, and databases. Logical storage devices are created and presented to the host application 104 for storage of the host application data. For example, in some embodiments, a production device 140 and a corresponding host device 142 are created to enable the storage system 100 to provide storage services to the host application 104.
The host device 142 is a local (to host computer 102) representation of the production device 140. Multiple host devices 142 associated with different host computers 102 may be local representations of the same production device 140. The host device 142 and the production device 140 are abstraction layers between the managed drives 132 and the host application 104. From the perspective of the host application 104, the host device 142 is a single data storage device having a set of contiguous fixed-size LBAs (logical block addresses) on which data used by the host application 104 resides and can be stored. However, the data used by the host application 104 and the storage resources available for use by the host application 104 may actually be maintained by the compute nodes 1161-1164 at non-contiguous addresses on various different managed drives 132 on storage system 100.
In some embodiments, the storage system 100 maintains metadata that indicates, among various things, mappings between the production device 140 and the locations of extents of host application data in the shared global memory 138 and the managed drives 132. In response to an IO (input/output command) 146 from the host application 104 to the host device 142, the hypervisor/OS 112 determines whether the IO 146 can be serviced by accessing the host computer memory 106. If that is not possible then the IO 146 is sent to one of the compute nodes 116 to be serviced by the storage system 100.
There may be multiple paths between the host computer 102 and the storage system 100, e.g. one path per front end adapter 126. The paths may be selected based on a wide variety of techniques and algorithms including, for context and without limitation, performance and load balancing. In the case where IO 146 is a read command, the storage system 100 uses metadata to locate the commanded data, e.g. in the shared global memory 138 or on managed drives 132. If the commanded data is not in the shared global memory 138, then the data is temporarily copied into the shared global memory 138 from the managed drives 132, and sent to the host application 104 via one of the compute nodes 1161-1164. In the case where the IO 146 is a write command, in some embodiments the storage system 100 copies a block being written into the shared global memory 138, marks the data as dirty, and creates new metadata that maps the address of the data on the production device 140 to a location to which the block is written on the managed drives 132. The shared global memory 138 may enable the production device 140 to be reachable via all of the compute nodes 1161-1164 and paths, although the storage system 100 can be configured to limit use of certain paths to certain production devices 140.
If a compute node receives an IO, the compute node will access the metadata for the IO to determine where the data is stored on the disk array (which array, which disk, which track) and then issue the memory access operation on the disk array. If the compute node does not have the metadata and the metadata is contained in the memory of another compute node, it will need to first retrieve the metadata from the other compute node. As described in greater detail herein, a storage system is proposed in which each compute node is able to perform atomic operations and RDMA operations on each memory of every other compute node without requiring intervention by the other compute node.
In some embodiments, the fabric interface manager 170 includes a NVMeoF (Non-Volatile Memory express over Fabrics) initiator. NVMeoF is a network protocol, like iSCSI, used to communicate between a host and a storage system over a network (aka fabric). In some embodiments, the NVMeoF initiator initiates transactions on the fabrics 136, for example to perform read and write transactions on disk arrays 130.
In some embodiments, the fabric interface manager 170 includes RDMA manager 174. RDMA (Remote Direct Memory Access) is a direct memory access operation from the memory of one compute node 116 into that of another compute node 116 without involving either one's operating system. RDMA manager 174 manages RDMA operations targeting memory 124 on compute node 116. RDMA manager 174 also manages RDMA operations by compute node 116 on memories 124 of other compute nodes in the storage system 100. Since all compute nodes 116 can implement memory access operations on local memory 124 of each of the other compute nodes, without requiring the other compute node 116 to become involved in the memory access operation, the memory access operation is greatly simplified, thus improving the efficiency of the storage engine 118 and reducing latency in accessing data.
In some embodiments, the fabric interface manager 170 includes atomic manger 176. Atomic operations by CPU 122 on compute node 116 are managed by atomic manager 176. Similarly, atomic operations by other compute nodes on memory 124 of compute node 116 are implemented using atomic manager 176. In some embodiments, any compute node connected to fabric 136 can initiate atomic operations on the memory 124 of the associated compute node. Atomic manager 176 serializes operation by multiple nodes on the same address that are received from the fabric, guaranteeing the atomic nature of the operations.
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In some embodiments, fabric access module 128 includes a DIF (Data Integrity Field) check/generator 178. DIF is an approach to protecting data integrity in a computer data storage, that seeks to prevent data corruption. DIF generator aspect of DIF check/generator 178, in some embodiments, adds DIF information such as a hash of the data or a cyclic redundancy code, when the data passes through fabric access module 128 onto fabric 136. The added DIF information enables a recipient to determine whether data has been corrupted. The DIF check aspect of the DIF check/generator 178 uses DIF information contained in data that is received by fabric access module 128 from fabric 136, to determine whether the data has been corrupted. By adding DIF check information and using the DIF check information, the fabric access module 128 can help ensure the integrity of the data as the data is passed between components of the storage system 100.
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The methods described herein may be implemented as software configured to be executed in control logic such as contained in a Central Processing Unit (CPU) or Graphics Processing Unit (GPU) of an electronic device such as a computer. In particular, the functions described herein may be implemented as sets of program instructions stored on a non-transitory tangible computer readable storage medium. The program instructions may be implemented utilizing programming techniques known to those of ordinary skill in the art. Program instructions may be stored in a computer readable memory within the computer or loaded onto the computer and executed on computer's microprocessor. However, it will be apparent to a skilled artisan that all logic described herein can be embodied using discrete components, integrated circuitry, programmable logic used in conjunction with a programmable logic device such as a Field Programmable Gate Array (FPGA) or microprocessor, or any other device including any combination thereof. Programmable logic can be fixed temporarily or permanently in a tangible computer readable medium such as random-access memory, a computer memory, a disk, or other storage medium. All such embodiments are intended to fall within the scope of the present invention.
Throughout the entirety of the present disclosure, use of the articles “a” or “an” to modify a noun may be understood to be used for convenience and to include one, or more than one of the modified noun, unless otherwise specifically stated.
Elements, components, modules, and/or parts thereof that are described and/or otherwise portrayed through the figures to communicate with, be associated with, and/or be based on, something else, may be understood to so communicate, be associated with, and or be based on in a direct and/or indirect manner, unless otherwise stipulated herein.
Various changes and modifications of the embodiments shown in the drawings and described in the specification may be made within the spirit and scope of the present invention. Accordingly, it is intended that all matter contained in the above description and shown in the accompanying drawings be interpreted in an illustrative and not in a limiting sense. The invention is limited only as defined in the following claims and the equivalents thereto.
