Abstract: A storage system performs garbage collection, with data compression, in storage memory. The system obtains hash results from data segments. The system determines similarity of content of data segments, based on the hash results. The system performs data compression of live data of two or more data segments that have similarity of content meeting a similarity threshold. The system writes the compressed live data of the two or more data segments into the storage memory.

Abstract: A geographically distributed erasure coding system includes multiple computer readable, non-transitory storage memories capable of storing a digital dataset including multiple object blocks, where each storage memory is configured to store one or more of the object blocks of the dataset according to an erasure coding policy. The system includes one or more processors configured to implement the erasure coding policy by distributing the multiple object blocks of the dataset to the multiple storage memories according to distribution criteria of the erasure coding policy, and the distribution criteria include at least one status parameter associated with each storage memory. The multiple storage memories are geographically distributed at different locations from one another.

Abstract: An object-based data storage service receives a request to store a data object in association with a smart data storage tier. Based at least in part on characteristics of the data object, the object-based data storage service identifies and stores the data object in a first location corresponding to a first data storage tier. The object-based data storage service monitors access to the data object to identify a second set of characteristics of the data object. This second set of characteristics is used to determine that the data object is to be transitioned to a second data storage tier. The object-based data storage service, based at least in part on this determination, stores the data object in a second location corresponding to the second data storage tier.

Abstract: Methods and apparatus for platform ambient data management schemes for tiered architectures. A platform including one or more CPUs coupled to multiple tiers of memory comprising various types of DIMMs (e.g., DRAM, hybrid, DCPMM) is powered by a battery subsystem receiving input energy harvested from one or more green energy sources. Energy threshold conditions are detected, and associated memory reconfiguration is performed. The memory reconfiguration may include but is not limited to copying data between DIMMs (or memory ranks on the DIMMS in the same tier, copying data between a first type of memory to a second type of memory on a hybrid DIMM, and flushing dirty lines in a DIMM in a first memory tier being used as a cache for a second memory tier. Following data copy and flushing operations, the DIMMs and/or their memory devices are powered down and/or deactivated.

Abstract: A system related to providing multi-layer code rates for special event protection with reduced performance penalty for memories is disclosed. Based on an impending stress event, extra error correction code data is utilized to encode user data obtained from a host. The user data and first error correction code data are written to a first block and the extra error correction code data is written to a second block. Upon stress event completion, pages having user data with the extra error correction code data are scanned. If pages of the first block are unable to satisfy reliability requirements, a touch-up process is executed on each page in the first block to reinstate the first block so that the extra error correction code data is no longer needed. The extra error correction code data is deleted from the second block and the second block is made available for user data.

Abstract: A technique to control write operations in a logical partition. For example, a device can receive a user specified write threshold for the logical partition that is hosted on a pool of memory cells shared by a plurality of logical partitions in wear leveling. An accumulated amount of data written into the memory cells according to write requests addressing the logical partition is tracked. In response to the accumulated amount reaches the write threshold, further write requests addressing the logical partition can be blocked, rejected, and/or ignored. For example, the logical partition can be used to buffer data for time shift in playing back content streaming from a server. Write operations for time shift can be limited via the user specified threshold to prevent overuse of the total program erasure budget of the pool of memory cells shared with other logical partitions.

Abstract: A transaction processing method and apparatus, a computer device, and a storage medium, improve transaction processing efficiency. When read and write operations of a target transaction are executed, a concurrent transaction of a target transaction can be obtained and used to determine whether a data anomaly exists based on read-write sets of the concurrent transaction and the target transaction. The read-write sets of the concurrent transaction and the target transaction can be merged to commit the target transaction. In this way, various data anomalies can be comprehensively detected, and data state consistency is ensured. The transaction processing method does not rely completely on locking technology nor on dependency graph technology, thereby preventing system concurrency from being limited, improving querying speed and modification speed of data, and improving transaction processing efficiency.

Abstract: It is possible to reduce analysis cost of a management system. The management system includes a CPU and manages one or more storage devices that provide, to a higher-level device, one or more volumes for inputting and outputting data. The CPU is configured to collect performance information of the volume from the storage device at a predetermined first time interval and detect a QoS violation of the performance information of the volume at a second time interval longer than the first time interval.

Abstract: Methods, systems, and apparatus, including computer programs, for a monitoring system that is configured to hail a car from a ride-sharing service. The method comprises determining, based on sensor data from one or more sensors at the property, that a person located at the property is preparing to leave the property, based on historical sensor data, an estimated time that the person will depart the property, determining, based on the estimated time that the person will depart the property, whether a suitable vehicle from a ride-sharing service will be within a predetermined vicinity of the property within a predetermined amount of time of the estimated time that the person will depart the property, receiving data indicating that the person is leaving the property and based on receiving the data indicating that the person is leaving the property, notifying the person that the suitable vehicle is available pick the person up.

Abstract: Methods and systems include processors and hardware accelerators. The processor initiates a first process in a first hardware accelerator configured to aid the processor in performing the first process. The processor initiates the first process using one or more interface registers. The processor performs additional processing while the first hardware accelerator performs the first process after initiation of the first process. The processor also initiates a second process in a second hardware accelerator configured to aid the processor in performing a second process. Moreover, the processor initiates the second process using the one or more interface registers.

Abstract: An access tracker configured to receive a request to access a page, determine whether a page identification (ID) associated with the page is in the access tracker, increment an access count of the page in response to determining the page ID is in the access tracker, sort a number of page IDs based on an access count of each page ID, and determine whether a different page is hot or cold in response to sorting the number of page IDs.

Abstract: Methods, apparatus, systems and articles of manufacture are disclosed for efficient media indexing. An example method disclosed herein includes means for initiating a list of hash seeds, the list of hash seeds including at least a first hash seed value and a second hash seed value among other hash seed values, means for generating to generate a first bucket distribution based on the first hash seed value and a first hash function and generate a second bucket distribution based on the second hash seed value used in combination with the first hash seed value, means for determining to determine a first entropy value of the first bucket distribution, wherein data associated with the first bucket distribution is stored in a first hash table and determine a second entropy value of the second bucket distribution.

Abstract: Systems and methods for performing single I/O writes are provided. According to one embodiment, responsive to receipt of a write operation from a client by a file system layer of a node of a distributed storage system and a data payload of the operation having been determined to meet a compressibility threshold, an intermediate storage layer of the node logically interposed between the file system layer and a block storage media is caused to perform a single input/output (I/O) write operation that persists the compressed data payload and corresponding metadata to support asynchronous journaling of the write operation. The single I/O write operation coupled with the use of a new pool file that maintains a list of available blocks for single I/O write operations and a modified node crash recovery approach allows the write operation to be acknowledged to the client while the journaling is performed asynchronously.

Abstract: According to one embodiment, a storage device is configured to store unencrypted user data. The user data is erased according to at least one data erasure mechanism. The storage device comprises a receiver configured to receive an inquiry from a host device, and a transmitter configured to transfer response information indicating the at least one data erasure mechanism to the host device.

Abstract: Techniques are provided for a layout format for compressed data. A first set of data blocks are grouped into a first group based upon a first frequency of access to the first set of data blocks. A second set of data blocks are grouped into a second group based upon a second frequency of access to the second set of data blocks. The first set of data blocks are compressed into a first compression group using a first compression algorithm. The second set of data blocks are compressed into a second compression group using a second compression algorithm.

Abstract: A first node receives a read request, determines a storage drive location where data corresponding to one or more logical addresses designated in the read request is stored, and requests transfer of the data at the one or more logical addresses, from the second node, when the storage drive location is the second node. The second node reads a data chunk containing the data designated by the one or more logical addresses, from one or more storage drives, determines whether to decompress the data chunk based on the size of the data chunk and the size of the one or more logical addresses, decompresses the data chunk based on the determination as to decompress the data chunk, extracts data at the one or more logical addresses, and transfers the extracted data to the first node.

Abstract: Techniques for efficiently exporting snapshot changes are provided. In some embodiments, a system may receive a first snapshot of a data set in a storage system and a second snapshot the data set in the storage system. The system may further generate actions based on differences between the first snapshot and the second snapshot to produce a list of actions, wherein a modification to a file or directory path having a first directory location includes a first action to rename a file from the first directory location to a temporary storage location and a second action to rename the file from the temporary storage location to a second directory location; and provide the generated actions to a backup system. The backup system may apply the generated actions to a first backup associated with the first snapshot to produce a second backup associated with the second snapshot.

Abstract: A computer system stores management information that manages a workflow and a deletion flag that indicates deletion of data in the workflow hidden from a user. The computer system executes a workflow that includes one or more processes that convert input data into output data. The computer system includes a lineage of the executed workflow including information of the input data and the output data in the management information. The computer system deletes data selected from data in the executed workflow, and sets the deletion flag of the selected data in the management information. The computer system, in response to an access to first data to which the deletion flag is set, regenerate the first data based on the management information and removes the deletion flag of the first data in the management information.

Abstract: Methods, apparatus, systems and articles of manufacture to compress data are disclosed. An example apparatus includes a data slicer to split a dataset into a plurality of blocks of data; a data processor to select a first compression technique for a first block of the plurality of blocks of data based on first characteristics of the first block; and select a second compression technique for a second block of the plurality of blocks of data based on second characteristics of the second block; a first compressor to compress the first block using the first compression technique to generate a first compressed block of data; a second compressor to compress the second block using the second compression technique to generate a second compressed block of data; and a header generator to generate a first header identifying the first compression technique and a second header identifying the second compression technique.

Abstract: A processing system includes a primary processor and a co-processor. The primary processor is couplable to a memory subsystem having at least one memory and operating to execute system software employing memory address translations based on one or more page tables stored in the memory subsystem. The co-processor is likewise couplable to the memory subsystem and operates to perform iterations of a page table walk through one or more page tables maintained for the memory subsystem and to perform one or more page management operations on behalf of the system software based the iterations of the page table walk. The page management operations performed by the co-processor include analytic data aggregation, free list management and page allocation, page migration management, page table error detection, and the like.

Abstract: A method, an electronic device, and a computer program product for data management is disclosed. The method includes receiving a request for performing, on data, a first management operation related to a first storage device, the request indicating a type of the data. The method further includes determining a first service associated with the type of the data and enabling the first service to perform the first management operation on the data. Thus, resource consumption of a data manager at runtime may be substantially reduced, which saves resources to reduce operating cost of the data manager, and improves the user experience of users who use the data manager.

Abstract: Methods, systems, and devices for performing data migration operations using a memory system are described. The memory system may include a data migration component, such as a driver, for facilitating the transfer of data between a first memory device that may implement a first memory technology (e.g., having a relatively fast access speed) and a second memory device that may implement a second memory technology (e.g., having a relatively large capacity). The component may indicate the data migration operation to a second component (e.g., a controller) of the memory system. The second component may initiate the transfer of data between the first memory device and the second memory device based on the receiving the indication of the data migration operation. In some cases, the transfer of data between the first memory device and the second memory device may occur within the memory system without being transferred through a host device.

Abstract: Dynamic configuration of storage volumes based on data usage metrics is provided. Data may be initially written to a relatively low-throughput storage volume that is managed according to a usage metric. For example, a burst balance metric may be monitored and, if it falls below a threshold or reduces at a rate exceeding a threshold, the system can dynamically change to writing data to a higher-throughput data storage volume. After a period of time and/or if performance criteria are satisfied, the system can dynamically change to writing data to a lower-throughput data storage volume.

Abstract: A method and apparatus for managing buffering of data packets of a network card, a terminal and a storage medium are provided. The method includes: setting ring buffer queues, setting a length of each ring buffer queue, then setting a buffer pool formed by two ring buffer queues, and setting the two ring buffer queues in the buffer pool as a busy queue and an idle queue, respectively; a network card driver receiving data packets from a data link, classifying the data packets, sequentially buffering the classified data packets into the busy queue, and then sequentially mapping addresses of the buffered data packets in the busy queue into the idle queue; acquiring latest addresses of the buffered data packets in the busy queue; and the upper-layer application successively acquiring and processing the buffered data packets, and successively releasing the addresses of the processed buffered data packets in the busy queue.

Abstract: An apparatus includes at least one processing device configured to identify a logical storage volume stored across multiple storage nodes of a distributed storage system, and for each of a plurality of different portions of the logical storage volume, to send one or more locality determination commands to each of one or more of the storage nodes, a given such command requesting a corresponding one of the storage nodes to respond with an indication as to whether or not the portion of the logical storage volume is local to that storage node, and to receive from the one or more storage nodes responses to the one or more locality determination commands. The processing device is further configured to store locality information for the plurality of different portions of the logical storage volume based at least in part on the responses of the storage nodes to the locality determination commands.

Abstract: Storage redundancy may be resynchronized without determining a snapshot difference. A storage component (210) owning a volume (122) can maintain current and expected generation numbers (212, 214) based on modification requests received and modification requests that a backup component (220) acknowledges completing. The backup (220) can maintain current and expected generation numbers (222, 224) based on modification requests received and applied to a backup volume (124). If either component (210, 220) fails and later returns to service, differences between the owner's current and expected generation numbers (212, 214) and the backup's current and expected generation numbers (222, 224) indicate which modification requests may have been missed and need to be reconstructed to restore synchronization.

Abstract: Various embodiments described herein provide for using a prefetch buffer with a cache of a memory sub-system to store prefetched data (e.g., data prefetched from the cache), which can increase read access or sequential read access of the memory sub-system over that of traditional memory sub-systems.

Abstract: A semiconductor device includes a first chip, a plurality of second chips, and a plurality of first signal lines. The first chip is electrically connected to a terminal group that receives a first signal from a host. The second chips are electrically connected to the first chip and are capable of outputting respective ready/busy signals. The ready/busy signals can be transferred through the first signal lines. Each of the second chips is respectively connected to the first chip through a corresponding first signal line among the plurality of first signal lines.

Abstract: A memory system includes a memory device and a processing device, operatively coupled to the memory device. The processing device performs operations comprising: identifying an operating temperature of the memory device; determining that the operating temperature satisfies a temperature condition; modifying a scan frequency parameter for performing a scan operation on representative blocks of a set of blocks in the memory device; and performing the scan operation at a frequency identified by the scan frequency parameter.

Abstract: A method is for operating a nonvolatile dual in-line memory module (NVDIMM). The NVDIMM includes a dynamic random access memory (DRAM) and a nonvolatile memory (NVM) device, the DRAM including a first input/output (I/O) port and a second I/O port, and the second I/O port connected to the NVM device. The method includes receiving an externally supplied command signal denoting a read/write command and a transfer mode, driving a multiplexer to select at least one of the first and second I/O ports according to the transfer mode of the command signal, and reading or writing data according to the read/write command of the command signal in at least one of the DRAM and NVM device using the at least one of the first and second I/O ports selected by driving the multiplexer.

Abstract: A geographically distributed erasure coding system includes multiple computer readable, non-transitory storage memories capable of storing a digital dataset including multiple object blocks, where each storage memory is configured to store one or more of the object blocks of the dataset according to an erasure coding policy. The system includes one or more processors configured to implement the erasure coding policy by distributing the multiple object blocks of the dataset to the multiple storage memories according to distribution criteria of the erasure coding policy, and the distribution criteria include at least one status parameter associated with each storage memory. The multiple storage memories are geographically distributed at different locations from one another.

Abstract: A processing device in a host system monitors a data temperature of a plurality of memory pages stored in a host-addressable region of a cache memory component operatively coupled with the host system. The processing device determines that a first memory page of the plurality of memory pages satisfies a first threshold criterion pertaining to the data temperature of the first memory page and sends a first migration command indicating the first memory page to a direct memory access (DMA) engine executing on a memory-mapped storage component operatively coupled with the cache memory component and with the memory-mapped storage component via a peripheral component interconnect express (PCIe) bus. The first migration command causes the DMA engine to initiate a first DMA transfer of the first memory page from the cache memory component to a host-addressable region of the memory-mapped storage component.

Abstract: A method for mapping LUNs (logical unit numbers) in storage memory, performed by a storage system, is provided. The method includes determining a set of LUNs in the storage memory and generating a mapping from a logical address space to all of the LUNs in the set, based on the determining, so that each logical address in the logical address space maps to one LUN in the set. The method includes accessing one or more of the LUNs in accordance with the mapping.

Abstract: Embodiments are directed to managing data in a file system that includes a plurality of storage nodes and a plurality of storage volumes in a cloud computing environment. Metrics associated with each storage volume may be monitored. In response to the metrics exceeding a threshold value, performing further actions, including: determining storage volumes that are unhealthy based on the metrics that exceed the threshold value; updating metadata associated with the storage volumes to indicate that the storage volumes are unhealthy; decoupling the unhealthy storage volumes from storage nodes coupled to the unhealthy storage volumes; determining replacement storage volumes based on the metadata associated with the unhealthy storage volumes; updating other metadata associated with the replacement storage volumes to indicate that the replacement storage volumes are healthy storage volumes; and coupling the healthy storage volumes with the storage nodes that were coupled to the unhealthy storage volumes.

Abstract: Techniques involve determining the number of disks in a Redundant Array of Independent Disks (RAID) storage system, and the storage system comprises multiple types of mixed disks. The techniques further involve determining a target number of RAID sets to be allocated in the storage system according to the number of disks and a predetermined threshold, and then allocating the multiple types of disks to the RAID sets according to the target number and types of disks. Such techniques propose a way to allocate mixed disks to the corresponding RAID sets. When the RAID set grouping is performed to mixed disks of the storage system, the same type of disks are allocated in the same RAID set as much as possible, thereby improving the performance of the storage system.

Abstract: A semiconductor storage device includes a first memory die. The first memory die includes a first memory plane including a plurality of first memory blocks, a second memory plane including a plurality of second memory blocks, a first sequencer, and a second sequencer. The first sequencer is configured to start a first write sequence with respect to one of the first memory blocks in response to a first command set designating the one of the first memory blocks if no write sequence is being performed by the first sequencer. The second sequencer is configured to start a second write sequence with respect to one of the second memory blocks in response to a second command set designating the one of the second memory blocks if the first sequencer is performing the first write sequence and no write sequence is being performed by the second sequencer.

Abstract: Methods and systems are provided for assigning nodes to execute functions in a serverless computing environment. In one embodiment, a method is provided that includes receiving a function for execution in a serverless computing environment and identifying a storage pool needed during execution of the function. The serverless computing environment may include nodes for executing functions and a first set of nodes may be identified that implement the storage pool. Colocation measures may be determined between the first set of nodes and a second set of nodes. Available computing resources may be determined for the second set of nodes, such as available processing cores and available memory. The second set of nodes may be ranked according to the colocation measures and the available computing resources and a first node may be selected based on the ranking. The first node may be assigned to execute the function.

Abstract: A USB-based cloud disk according to an embodiment is connected with a computer, and, when a write command on a sector is received from the computer, the USB-based cloud disk transmits data regarding the sector and a data path regarding the sector data to a remote repository.

Abstract: A method includes acquiring, by a managing unit of a dispersed storage network (DSN), storage unit status information and data object storage status information from a plurality of storage units of DSN memory of the DSN. The method further includes determining, by the managing unit, DSN status information of the DSN memory based on the storage unit status information and the data object storage status information. The method further includes identifying, by the managing unit, DSN memory issues within the DSN memory. The method further includes prioritizing, by the managing unit, corrective remedies for the DSN memory issues based on the status information of the DSN memory. The method further includes facilitating, by the managing unit, the execution of the prioritized corrective remedies to correct the DSN memory issues.

Abstract: A method, a device, and a computer program product for creating a stripe in a storage system. In the method, a balance index of a storage device in multiple storage devices in the storage system is determined. Here, the balance index indicates a relationship between the state distribution of a set of stripes which have been allocated for use in the storage device and the state distribution of a set of stripes which have been allocated for use in the multiple storage devices. An influence factor for the balance index of the storage device in the multiple storage devices is determined according to attributes of the storage device in the multiple storage devices. A storage device for creating a stripe is selected from the multiple storage devices based on the determined balance index and the determined influence factor. One extent in the selected storage device is added to the stripe.

Abstract: A method for updating software of storage units of a set of storage units in a storage network. In an embodiment, each storage unit of the set of storage units determines a data slice storage status for data slices stored in the storage unit (e.g., by monitoring rebuilding messages relating to the data slices). A processing module of the storage network obtains the data slice storage status of the storage units of the set of storage units and determines whether to perform a software update to software of the storage units of the set of storage units. Determining whether to perform the software update includes determining, based on the data slice storage status of the storage units, whether a threshold number of storage units are associated with a favorable data slice storage status. In response to determining that a threshold number of storage units are associated with a favorable data slice storage status, the processing module indicates to perform the software update.

Abstract: A storage device includes; an interface receiving data and a corresponding LBA from a host, wherein the data includes at least one of first data having a stream ID and second data lacking a stream ID, a nonvolatile memory (NVM) device including at least one nonvolatile memory configured to store the data, and a LBA predictor configured to provide a predicted stream ID for the second data using a neural network model operating in response to at least one feature associated with LBA values received by the storage device from the host, wherein the first data is stored in the NVM device using the stream ID, and the data is stored in the NVM device using the predicted stream ID.

Abstract: Improved management of user based input to a converged portable communication device is provided. A primary processor is configured to detect a user input feature request in response to a user interface control being activated. The primary processor determines whether the user input feature request is one of: a primary processor-centric request or a secondary processor-centric request. The primary processor retains primary requests and routes secondary requests to a secondary processor. If the secondary processor is unable to perform the requested feature, a check is made whether the primary processor is available and can fulfill the request as a secondary request. Positive user feedback is generated in response to determine that requests can be handled, and negative user feedback is generated when a requested feature cannot be handled.

Abstract: A copy-free transition tool converts storage objects from a source format associated with a source storage system to a destination format associated with a destination storage system. The transition tool exports configuration information associated with the source storage system to the destination storage system and brings the storage objects offline. Once the transition tool determines that the storage devices containing the storage objects are physically connected to the destination storage system, the tool can convert file systems from the source format to the destination format while leaving data and file layout unchanged. The tool can also modify metadata associated with each of the storage objects to conform to the destination format and store the modified metadata with the destination storage system.

Abstract: A method for optimizing memory usage in a device having a universal controlling application includes receiving into the device data for use in configuring the universal controlling application wherein the data is used to identify from within a library of command code sets stored in a memory of the device a command code set that is appropriate for use in commanding functional operations of the appliance and causing a non-identified one or more of the command code sets of the library of command code sets stored in the memory of the device to be discarded to thereby create freed space in the memory of the device.

Abstract: A dispersed storage (DS) unit for use within a dispersed storage network is capable of self-configuring using registry information provided to the DS unit. The registry information includes a slice name assignment indicating a range of slice names corresponding to a plurality of potential data slices of potential data objects to be stored in the DS unit. Based on the registry information, the DS unit allocates a portion of physical memory to store the potential data slices.

Abstract: Dynamically creating a communication path between first and second storage devices, includes creating a connection to a source volume on the first storage device and indicating that the source volume is not ready to transmit data on the communication path, after successfully creating the connection to the source volume, creating a connection to a destination volume on the second storage device and initially indicating that portions of one of: the destination volume and the source volume do not contain valid copies of data, where the destination volume accepts data from the source volume, and after successfully creating the connections to the source and destination volumes, indicating that the source volume is ready to transmit data on the communication path. Dynamically creating a communication path between first and second storage devices, may also include creating at least one of: the source volume and the destination volume.

Abstract: An electronic apparatus includes a memory control part that carries out allocation and deallocation of a memory area in a memory space; a memory reorganization part that carries out a reorganization process of moving the memory area allocated by the memory control part and creating a contiguous free space in the memory space; and a reorganization control part that causes the reorganization part to carry out the reorganization process in a case where a first predetermined condition is met, and does not cause the reorganization part to carry out the reorganization process in a case where a second predetermined condition different from the first predetermined condition is met.

Abstract: Replicated data storage units are autonomously identified and assembled into generationally related data storage volumes. A data storage manager, implementing a re-signaturing process executed at defined intervals or manually initiated on a server or client system connected to the storage area network, scans the collection of visible data storage units to identify those related as a data storage volume. Each replicated data storage unit includes metadata that embeds an identification of the replicated data storage unit and volume accessible to the data storage manager. To assemble a set of replicated data storage units into a generational volume, the data storage unit metadata is rewritten to establish a unique data storage volume identity including information to associate the data storage volume in a lineage with the source data storage volume.

Abstract: Described are techniques for enforcing an allocation policy. Information is received that describes one or more storage groups. Each of the storage groups includes one or more thin devices. Each of the thin devices includes a plurality of chunks of storage allocated on one or more of a plurality of storage tiers. For each of the one or more storage groups, a plurality of counters is determined indicating amounts of storage currently allocated from the plurality of storage tiers for use by the storage group. Using the plurality of counters, it is determined whether each of the one or more storage groups violates thresholds included in an allocation policy associated with each storage group. Each of the thresholds specifies a maximum amount of storage of one of the plurality of storage tiers that can be used by each storage group.