Emc IP Holding Company LLC

Dell Products Inc.

Emp IP Holding Company LLC

Lior Kamran

Amitai Alkalay

Vladimir Shveidel

Alex Soukhman

Zvi Schneider

Vamsi K Vankamamidi

Steven A Morley

Oran Asher Baruch

Aric Hadav

David Krakov

Marcelo Taube

Anton Kucherov

Eldad Zinger

Tal Ben-Moshe

Nimrod Shani

Leron Fliess

Niko Farhi

Hillel Costeff

Amihay Azruel

Uri Shabi

Ronen Gazit

Leonid Ravich

Vasu Subramanian

Vladimir Kleiner

Vitaly Zharkov

Liran Loya

Boris Glimcher

Alexander Barabash

Amir Miron

Amir Kredi

Regulating maintenance background (BG) task activity using instrumented waiting points (WPs) can include: collecting feedback metrics for the WPs, where each WP is instrumented to collect a set of feedback metrics including an average waiting time and a first value denoting a portion of resource requests received at the WP which are from maintenance BG tasks; determining, in accordance with criteria and collected feedback metrics, whether the criteria is true for at least a first WP associated with a set of feedback metrics, wherein the criteria includes determining whether the first WP has an associated average waiting time of the set which exceeds a waiting time threshold, and whether the first WP has a share of maintenance BG requests exceeding a minimum; and responsive to determining that the criteria is true for at least the first WP, performing processing to reduce a current activity level of said maintenance BG tasks.

Maintenance background task regulation using feedback from instrumented waiting points

System-level garbage collection is performed in an SSD-based data storage system employing log-structured writing of data. Respective reclaim unit sizes of the storage devices are identified, wherein each reclaim unit is a unit of programming and erasure used by device-level garbage collection to generate erased reclaim units for allocation for physical data storage. The data is arranged across the storage devices in first and second data units, each first data unit being of a first size U equal to the product of R and a stripe width W, each second data unit including a respective set of first data units which occupy a maximum-size reclaim unit of a storage device among those storing the first data units. The system-level garbage collection is operated with second-data-unit granularity to regularly generate empty second data units for allocation in the log-structured writing of data, reducing write amplification and device wear.

Log-structured data storage system using flexible data placement for reduced write amplification and device wear

Techniques for reducing power consumption in a storage system that includes a disk array enclosure (DAE). The techniques include selecting a number of active drives for inclusion in an active drive subgroup of the DAE, and designating a number of inactive (OFF or non-operational) drives for inclusion in an inactive drive subgroup of the DAE. The total number of drives included in the DAE equals the sum of the number of active drives and the number of inactive drives. The techniques further include monitoring at least one condition (e.g., storage capacity utilization, drive wear-leveling, system performance) pertaining to a power consumption of the storage system, and reducing the power consumption by dynamically adapting the number of active drives in the active drive subgroup based on the monitored condition. By dynamically adapting the number of active drives based on certain storage system conditions, significant reductions in power consumption can be achieved.

Power consumption reduction in storage system

A technique is directed to providing endurance to solid state device (SSD) storage. The technique involves storing data in an erase block of the SSD storage. The technique further involves detecting that an internal periodic refresh service operating within the SSD storage is currently configured to perform a refresh operation for the erase block at a target refresh time that is within an upcoming amount of time. The technique further involves, in response to detecting that the internal periodic refresh service is currently configured to perform a refresh operation for the erase block at the target refresh time that is within the upcoming amount of time, performing a system-level garbage collection operation on the data stored in the erase block to prevent the internal periodic refresh service from performing a refresh operation for the erase block at the target refresh time.

Providing endurance to solid state device storage

A technique is directed to managing wear leveling between storage devices. The technique includes obtaining a wear level metric of a candidate storage extent that includes storage from multiple storage devices. The technique further includes performing an assessment operation that provides an indication that the candidate storage extent satisfies an access criterion. The access criterion is based on the wear level metric. The technique further includes, in response to the assessment operation providing the indication that the candidate storage extent satisfies the access criterion, performing a set of access operations that accesses the candidate storage extent.

Managing storage extents using wear levels

Techniques manage data within storage equipment having a Flexible Data Placement (FDP) drive. The techniques involve configuring the storage equipment to support storing data in reclaim units of the FDP drive according to an initial group of reclaim unit handles. The techniques further involve detecting that a number of currently available reclaim units of the FDP drive has fallen below a first predefined threshold. The techniques further involve, in response to detecting that the number of currently available reclaim units of the FDP drive has fallen below the first predefined threshold, reconfiguring the storage equipment to support storing data in reclaim units of the FDP drive according to a smaller group of reclaim unit handles. The smaller group of reclaim unit handles has fewer reclaim unit handles than the initial group of reclaim unit handles.

Managing reclaim unit handles to control access to a flexible data placement drive

In at least one embodiment, processing can include: receiving, at a first node of a system, a cross slice border (CSB) I/O with a target location that crosses a CSB between two slices owned by different nodes; adding an entry for the CSB and CSB I/O to a cross border hash table (CBHT) of the first node; acquiring first locks for logical addresses of the first slice owned by the first node; sending a remote procedure call (RPC) to a second node requesting second locks for second logical addresses of the second slice owned by the second node; receiving an RPC reply in response to the RPC; and responsive to receiving an RPC reply indicating the negative acknowledgement, releasing the first locks and removing the entry from the CBHT of the first node.

Techniques for providing I/O atomicity and preventing deadlock for cross slice border I/Os in a distributed storage system

A technique is directed to managing wear leveling between storage devices. The technique includes generating a wear imbalance level indicating a variance between a first wear level of a first set of storage devices and a second wear level of a second set of storage devices. The technique further includes, after generating the wear imbalance level, performing a comparison operation that compares the wear imbalance level to a predefined imbalance threshold. The technique further includes, in response to the comparison operation indicating that the wear imbalance level is above the predefined imbalance threshold, providing the first set of storage devices as a first storage tier and the second set of storage devices as a second storage tier.

Managing wear levels of storage devices

A polling interval of a poller in a data storage system is dynamically adjusted to balance latency and resource utilization. Performance metrics are regularly estimated or measured and derived values are calculated including a latency share and a cost per event, based on a latency metric for polling latency and a cost metric for use of processing resources. A target latency share is adjusted by (1) an increase based on a CPU utilization metric being above a utilization threshold, and (2) a reduction based on the CPU utilization metric being below the utilization threshold and the cost per event being lower than a cost-per-event threshold. The polling interval is adjusted by (1) increasing the polling interval based on the latency share being less than the target latency share, and (2) decreasing the polling interval based on the latency share being greater than the target latency share.

Data storage system with dynamic adjustment of polling intervals

Techniques provide communication between storage processors (SPs) of a storage array. The techniques involve electrically coupling the SPs with an interconnect of the storage array. The techniques further involve electrically coupling a storage device having dual on-device controllers with the interconnect. The techniques further involve establishing a communications pathway between the SPs through the interconnect and the storage device having the dual on-device controllers while the SPs are electrically coupled with the interconnect and while the storage device is electrically coupled with the interconnect.

Providing communication between storage processors through an interconnect and a set of storage devices

Techniques can include: configuring a federation to have a volume as active from only a first storage system so that hosts only sends I/O operations, directed to the first volume, to the first storage system; configuring a second storage system of the federation as inactive with respect to volume; determining, in accordance with criteria, to allow I/O operations directed to the volume to be sent to both the first and second storage systems; transitioning the second storage system, with respect to the volume, from inactive to active; and receiving, from a host at the first and second storage systems, I/O operations directed to the volume while the first and second storage systems are configured as active. The I/O operations can include a first I/O operation received at the second storage system which is redirected, by the second storage system, to the first storage system for servicing.

Techniques for servicing I/O operations using redirection

A technique protects user data within a storage system. The technique involves, in response to a request signal that directs the storage system to store the user data, generating first parity and second parity based on the user data. The technique further involves storing the first parity and the user data in a data uber of the storage system, the data uber providing redundant array of independent disks (RAID) protection. The technique further involves storing the second parity in designated free storage of the storage system, the designated free storage being separate from the data uber.

Flexible RAID scheme allowing fast rebuild

Non-volatile data storage of a data storage system is organized into multiple RAID extents. Each RAID extent contains multiple logically contiguous RAID stripes. In response to detecting a failed drive in the data storage system, an initial rebuilding pass is performed on each one of the RAID extents. The initial rebuilding pass recovers data that was previously stored on the failed drive and was located within high priority RAID stripes in the RAID extent. After the initial rebuilding pass is completed on all of the RAID extents, at least one subsequent rebuilding pass is performed on each one of the RAID extents. The subsequent rebuilding pass recovers data that was previously stored on the failed drive and was located within RAID stripes in the RAID extent that are not high priority.

Priority based raid (redundant array of independent disks) rebuild for a data storage system

Techniques provide communications bandwidth between storage processors (SPs). Such techniques involve electrically coupling the SPs with a first side of a midplane. Such techniques further involve electrically coupling a network interface controller (NIC) device with a second side of the midplane that is opposite the first side of the midplane. Such techniques further involve configuring the NIC device to convey communications between the SPs while the SPs are electrically coupled with the first side of the midplane and while the NIC device is electrically coupled with the second side of the midplane that is opposite the first side of the midplane.

Scaling midplane bandwidth between storage processors via network devices

In at least one embodiment, a log-structured system for metadata (MD) updates can be leveraged to enable use of variable size MD pages with multiple different encoding formats. Processing can include: generating an updated MD page by performing one or more updates to an existing version of the MD page; selecting a first page type to be used for encoding the updated MD page, wherein said selecting selects the first page type from a plurality of predefined page types, wherein each of the plurality of predefined page types identifies a different metadata layout or format for storing MD pages; encoding the updated MD page in accordance with the first page type and accordingly generating a first encoded version of the updated MD page; and storing the first encoded version of the updated MD page at a first physical storage location of a non-volatile storage device.

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Rishon Lezion, Israel

Lior Kamran