Emc IP Holding Company LLC

Dell Products Inc.

Eldad Zinger

Leonid Ravich

Vitaly Zharkov

Ran Anner

Elad Grupi

Amit Engel

Amitai Alkalay

Lior Kamran

Dmitry Nikolayevich Tylik

Zvi Schneider

Kirill Shoikhet

Kobi Luz

Marina Shem Tov

Gilad Braunschvig

Alexander Barabash

Chen Reichbach

Or Idgar

Omer Dayan

Eyal Harari

Access control data stored in the storage servers of a distributed data storage system is modified according to received access control commands and accessed to process host I/O requests without requiring the use of locks. Processing of certain access control commands includes allocating a new volume descriptor to store the updated access control data for a corresponding storage volume, and remapping the storage volume to the new volume descriptor with a single write operation. Each volume descriptor stores both reservation type and reservation holder data for the corresponding storage volume within a single memory register, allowing host I/O request processing logic to read both reservation type and reservation holder using a single read operation, and access control command processing logic to modify both reservation type and reservation holder using a single write operation. A registrants bitmap in the volume descriptor represents hosts registered for the corresponding storage volume.

Access control command processing in a distributed data storage system

Deferred memory page allocation commands and non-deferred memory page allocation commands are identified within host I/O commands received by a data storage system. For each one of those received host I/O commands that are identified as a deferred memory page allocation command, QoS (Quality of Service) policy enforcement is performed before any memory pages are allocated by the data storage system to store host data indicated by the received command. Host I/O commands that are identified as deferred memory page allocation commands include read commands, and host I/O commands that are identified as non-deferred memory page allocation commands include in-capsule write commands. For commands identified as deferred memory page allocation commands, enforcing QoS policy before any memory pages are allocated to store host data indicated by the command avoids the possibility of enqueueing the allocated memory pages onto the QoS wait queue, thus conserving data storage system memory resources.

Quality of service (QOS) enforcement while conserving memory resources in a data storage system

Technology is disclosed for QoS (Quality of Service) enforcement with reduced contention. For commands where the QoS wait queue is empty and the QoS credit count is sufficient, an atomic operation subtracts the credits required to process the command from the QoS credit count without locking, and the command is processed. For other commands, credit generation is attempted by first reading a lock flag without obtaining a lock. If the lock flag is clear, an atomic operation sets it, and credit generation is performed if sufficient time has passed since a last credit generation. Credit generation stores a sum of the current QoS credit count and the number of newly generated credits into a local credit count, and processes commands in the QoS wait queue for which sufficient credits exist in the local credit count. When credit generation completes, the local credit count is stored into the QoS credit count.

Quality of service (QoS) enforcement with low contention command processing

A technique of managing the rate of I/O (Input/Output) request processing includes a token-bucket arrangement having first, second, and third token buckets. The first token bucket is provided with sufficient tokens to accommodate an expected baseline level of I/O requests, whereas the second token bucket is provided with sufficient tokens to accommodate an expected excess level of I/O requests during bursts. The third token bucket is provided with tokens at predefined intervals and limits a total amount of bursting available during those intervals.

Managing both baseline and burst I/O request rates

A technique of providing access to a namespace via multiple storage arrays involves providing access to the namespace from a nonvolatile memory (NVM) subsystem while the NVM subsystem is hosted on a first storage array. The technique further involves, after providing access to the namespace from the NVM subsystem while the NVM subsystem is hosted on the first storage array, performing a stretch operation to concurrently host the NVM subsystem on the first storage array and a second storage array. The technique further involves, after performing the stretch operation, providing access to the namespace from the NVM subsystem while the NVM subsystem is concurrently hosted on the first storage array and the second storage array. Accordingly, the namespace is now accessibly via either storage array.

Providing access to a namespace via multiple storage arrays

A method, computer program product, and computer system for exposing, by a user block layer of a computing device, a storage device as a block device to an application associated with an IO request. A Non-Volatile Memory Express (NVMe) protocol layer of the computing device may expose a NVMe storage device associated with the IO request to the user block layer. A NVMe-over-RDMA layer of the computing device may create a NVMe RDMA queue for the IO request to be processed.

System and method for user space NVMe-over-RDMA host library

A method, computer program product, and computing system for associating a plurality of NVMe IO submission queues with an NVMe IO completion queue. An NVMe IO completion queue polling frequency may be defined for a plurality of threads configured to provide one or more IO requests to the plurality of NVMe IO submission queues. The NVMe IO completion queue may be polled based upon, at least in part, the NVMe IO completion queue polling frequency defined for the plurality of threads.

System and method for processing requests in a multithreaded system

A method, computer program product, and computer system for directing, by a computing device, an incoming Non-Volatile Memory express (NVMe) command to a kernel driver. The kernel driver may enqueue the incoming NVMe command until fetched by a user space. The NVMe command may be fetched from the kernel driver for processing. The NVMe command may be pushed to a user space block device of the user space.

System and method for efficient scalable software-defined NVMEoF front-end connectivity

A method, computer program product, and computing system for receiving an input/output (IO) command for processing data within a storage system. An IO command-specific entry may be generated in a register based upon, at least in part, the IO command. An compare-and-swap operation may be performed on the IO command-specific entry to determine an IO command state associated with the IO command. The IO command may be processed based upon, at least in part, the IO command state associated with the IO command.

System and method for lockless aborting of input/output (IO) commands

A method, computer program product, and computer system for using, by a computing device, free central processing unit (CPU) cycles for processing Non-Volatile Memory express Over Fiber (NVMeoF)/Transmission Control Protocol (TCP) sockets. Using the free CPU cycles for processing the NVMeoF/TCP sockets may include exposing a character device with a callback that iterates over the NVMeoF/TCP sockets for processing.

System and method for boosting up performance of NVMe-TCP transport

A method, computer program product, and computing system for assigning a first set of interrupts for exclusive processing by a first set of central processing units (CPU) cores. A second set of interrupts may be assigned for processing by a second set of CPU cores. The first set of interrupts may be processed using the first set of CPU cores. The second set of interrupts may be converted to a set of polling operations, thus defining a set of converted polling operations. The set of converted polling operations may be processed using the second set of CPU cores.

System and method for polling-based storage command processing

Example embodiments of the present invention relate and a method and an apparatus for double hashing. The method including receiving a hash signature, including a short hash handle, for a data block. The method then includes determining a bucket with which the hash signature should be associated and associating the hash signature with the bucket.

Using double hashing schema to reduce short hash handle collisions and improve memory allocation in content-addressable storage systems

A method, computer program product, and computer system for maintaining a federation of a plurality of appliances as a single subsystem, wherein maintaining the federation as the single subsystem may include maintaining a centralized discovery mechanism across the plurality of appliances, wherein a discovery service of the centralized discovery mechanism may return a list of all ports in the federation. Controller IDs for a predefined range of controller IDs may be allocated for a plurality of dynamic controllers per appliance of the plurality of appliances, wherein the controller IDs may be allocated as a response to a connect command from a host. An empty namespace list for the plurality of dynamic controllers on the plurality of appliances in the federation may be exposed. The host may receive a notification from at least one dynamic controller of the plurality of dynamic controllers on at least one appliance of the plurality of appliances in the federation. The host may obtain a list of namespaces hosted on the at least one appliance corresponding to the at least one dynamic controller.

System and method for sustaining single NVMe subsystem by a federated storage array for NVMe-oF connectivity

A method, computer program product, and computing system for receiving a plurality of input/output (IO) commands for a plurality of configuration objects of a storage system. A modification command for a configuration object of the plurality of configuration objects may be received. The configuration object may be suspended in response to receiving the modification command. One or more IO commands directed to the suspended configuration object from the plurality of IO commands may be processed before the configuration object is modified.

System and method for suspending and processing commands on a configuration object

A method is disclosed comprising: instantiating, on a first device, a plurality of first connection objects; generating, by the first device, a first set of connection parameters that is associated with the plurality of first connection objects; transmitting the first set of connection parameters from the first device to a second device; receiving from the second device a second set of connection parameters, the second set of connection parameters being associated with a plurality of second connection objects that are instantiated on the second device; updating, by the first device, each of the first connection objects based on the second set of connection parameters; and transmitting, from the first device to the second device, a confirmation that a plurality of communications channels is established.

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Raanana, Israel

Eldad Zinger