Emc IP Holding Company LLC

Emc Corporation

Ronald D Proulx

Robert Foley

Peter Puhov

Ashok Tamilarasan

Wayne E Garrett, Jr

Marc C Cassano

Shaoqin Gong

Shuyu Lee

Eric Petsching

Jian Gao

Xinlei Xu

Geng Han

Vamsi K Vankamamidi

Jibing Dong

Hongpo Gao

Adi Ofer

Jamin Jianbin Kang

Daniel E Cummins

Baote Zhuo

Xiaobo Zhang

Naizhong Chiu

Techniques for storage management may include: adding first storage devices to a pool, wherein prior to adding the first storage devices to the pool, the pool includes second storage devices with existing physical storage units (PUs) distributed across the second storage devices; and in response to adding the first storage devices to the pool, performing processing to evenly distribute the existing PUs among the pool of storage devices, said processing including: defining logical pairs of storage devices in accordance with rules; binding each of the logical pairs to a resiliency set; determining that a first PU of the existing PUs includes disk slices that span across more than a single resiliency set; andin response to determining that the first PU includes disk slices that span across more than a single resiliency set, performing second processing to restripe the first PU in accordance with a target layout.

Techniques for storage management

A technique is directed to storing data on a plurality of storage devices of a data storage array. The technique involves, on each storage device of the plurality of storage devices, providing large disk extents and small disk extents for allocation to RAID extents. The technique further involves forming, from the large disk extents, a user-data RAID extent to store user data for the data storage array. The technique further involves forming, from the small disk extents, an internal-metadata RAID extent to store internal metadata for the data storage array. In some arrangements, spare space is reserved on one or more storage devices between large and small disk extents.

Simple and efficient technique to support disk extents of different sizes for mapped RAID

A method, computer program product, and computer system for receiving, by a computing device, an I/O request for data. A number of storage devices of a plurality of storage devices in a Mapped RAID group that will be used to process the I/O request may be determined. It may be determined that each storage device of the number of storage devices in the Mapped RAID group that will be used to process the I/O request lacks a respective threshold number of credits to process the I/O request. It may be determined whether a cache associated with the Mapped RAID group allows a user I/O queue. If the cache allows the user I/O queue, a user I/O may be placed in the user I/O queue. If the cache does not allow the user I/O queue, the I/O request may be failed.

System and method for improving I/O performance by introducing extent pool level I/O credits and user I/O credits throttling on Mapped RAID

A technique forms storage containers within a group of storage devices. The technique involves partitioning each storage device of the group of storage devices into slices having a same storage size. The technique further involves creating, from the slices having the same storage size, first extents having a first extent width and second extents having a second extent width. The first extent width is different from the second extent width. The technique further involves provisioning (i) at least one first extent from the first extents having the first extent width to form a first storage container within the group of storage devices and (ii) at least one second extent from the second extents having the second extent width to form a second storage container within the group of storage devices. The first storage container and the second storage container share at least one storage device.

Forming storage containers from extents having different widths within a group of storage devices

A technique rebuilds data from a group of hard disk drives (HDDs). The technique is performed in data storage equipment and involves storing data on a group of HDDs. The group of HDDs is constructed and arranged to maintain data availability following a HDD failure. The technique further involves, after storing the data on the group of HDDs, detecting a failure of a particular HDD of the group of HDDs. The technique further involves, after detecting the failure of the particular HDD, rebuilding a particular portion of data onto a solid state drive (SSD) based on other portions of the data residing on remaining HDDs of the group of HDDs other than the particular HDD, the particular portion of the data having resided on the particular HDD that failed.

Rebuilding data on flash memory in response to a storage device failure regardless of the type of storage device that fails

A method is used in managing data in a data storage system. A first set of flash drives in arranged into a redundant array of independent disks (RAID) group and a wear indicator for each of the flash drives in the first set of flash drives is determined. A second set of flash drives are configured, where the second set of flash drives are configured as spare flash drives and a wear metric is determined for each of the flash drives in the second set of flash drives. A first flash drive in the first set of flash drives that is to be replaced is identified. A spare flash drive from the second set of flash drives is selected, where the spare flash drive is selected based on a wear metric. A rebuild process is initiated where the first flash drive is replaced with the selected spare flash drive.

Intelligent sparing of flash drives in data storage systems

A technique is directed to providing resiliency to a redundant array of independent disk (RAID) group which includes multiple storage devices. The technique involves operating the RAID group in a normal state in which each storage device is (i) initially online to perform write and read operations and (ii) configured to go offline in response to a respective media error count for that storage device reaching an initial take-offline threshold. The technique further involves receiving a notification that a storage device of the RAID group has encountered a particular error situation. The technique further involves transitioning, in response to the notification, the RAID group to a high resiliency state in which each storage device that is operable is (i) still online to perform write and read operations and (ii) configured to stay online even when the respective media error count for that storage device reaches the initial take-offline threshold.

Providing resiliency to a raid group of storage devices

Technique provides resiliency to RAID group including storage devices. Technique involves operating RAID group in normal state in which each storage device is initially online to perform write and read operations and configured to go offline in response to a media error count for that storage device reaching an end-of-life threshold and other storage devices in RAID group being healthy. Technique involves receiving a notification that a storage device of RAID group has encountered an error situation. Technique involves determining whether other storage devices of RAID group are healthy. Technique involves transitioning, in response to receiving notification and determining that other storage devices are healthy, RAID group from normal state to high resiliency degraded state in which the storage device is taken offline and the other storage devices are configured to remain online for facilitating the reconstruction of data associated with the storage device.

Described are techniques for avoiding deadlock. Each consumer is assigned a priority level denoting a number of resource allocation requests that have been currently granted to the consumer. The priority level is incremented for each resource allocation request granted to the consumer. A set of common resource pool(s) and a reserved resource pool are provided. A wait list of pending resource requests made by the consumers is maintained. If no allocated resources of the set of common pool(s) have been released for at least a threshold amount of time and there is at least one request on the wait list, first processing is performed which includes selecting, in accordance with one or more criteria, a first pending resource request from the wait list that was made by a first consumer, and assigning the first consumer exclusive use of the reserved pool for a lifetime of the first consumer.

Deadlock avoidance techniques

A technique for managing storage device rebuild in a data storage system is disclosed. A RAID group having multiple drives with unique identifiers is provided. A drive in the RAID group that becomes inactive is identified and a timer is activated. A persistent bitmap is maintained, wherein the bitmap includes a plurality of bits and each bit indicates whether a corresponding portion of the identified drive has changed as a result of an I/O request issued while the drive is identified as inactive. If the inactive drive is subsequently identified as active before the timer expires, the timer is stopped and a rebuild procedure initiated, wherein only portions of the identified drive corresponding to bits in the bitmap are rebuilt. The bitmap is cleared and the RAID group is marked as healthy. If the timer expires before the identified drive become active, a full rebuild procedure is initiated.

Managing storage device rebuild in data storage systems

A method, computer program product, and computing system for sensing the occurrence of an uncorrectable condition within a data stripe of a RAID array. The data strip includes a plurality of data portions and a parity portion. One or more invalid data portions included within the plurality of data portions are identified. The one or more invalid data portions are populated with filler data having a known pattern, thus defining one or more filler portions. The parity portion is updated based, at least in part, upon the one or more filler portions, thus defining an updated data stripe that includes an updated parity portion.

Limiting data loss on parity RAID groups

Described are techniques for booting a data storage system. A first set of configuration and state information is read from first storage devices of a first RAID group using special processing code and a RAID library. A first set of system objects (of a system object topology) are instantiated using the first set of information. The first set of system objects represent storage entities containing a second set of configuration and state information. Using an I/O runtime stack based on the system object topology, the second set of information is read from second storage devices of a second RAID group using the same RAID library having calls made from method(s) of a RAID group object representing the second RAID group. A second set of client objects, instantiated using the second set of information, represent storage entities including client data stored on third storage devices of a third RAID group.

Data storage system configuration

A method is used in handling sector edges. Input/output (I/O) requests to a storage device are handled. The I/O requests use a different sector size format than that of the storage device. An I/O request is received for a write operation at a logical address of a virtual device. The write operation specifies new data to be written to the virtual device. A logical sector associated with the logical address is determined. The logical sector is mapped to a portion of a physical sector of the storage device. The sector edge of the physical sector is read into a RAID-protected memory. The read sector edge is written together with the new data to the storage device.

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Boxborough, MA, United States of America

Ronald D Proulx