Abstract: A constant value method for detecting and evaluating internal leakage in a hydraulic cylinder and a detection device. The method comprises: step (1) measuring an accurate pressure drop value ?p of the internal leakage in the hydraulic cylinder; step (2), determining whether the detected hydraulic cylinder meets a standard: if the product of the accurate pressure drop value ?p of the internal leakage in the hydraulic cylinder and a corresponding hydraulic stroke L, is less than a standard parameter C for evaluating the internal leakage in the hydraulic cylinder, C = 4 ? QtK ? ? D 2 , the internal leakage in me hydraulic cylinder meets the standard. Otherwise, the internal leakage in the hydraulic cylinder does not meet the standard. The detection device comprises a motor, a hydraulic pump, a directional valve, a detected part, a pipeline disassembly joint and a pressure sensor.

Abstract: The disclosure aims to provide a chemical synthesis method of a prodelphinidin B9 gallate, in which the prodelphinidin B9 gallate is synthesized by using a proanthocyanidin from Chinese bayberry leaves as a raw material, and using epigallocatechin gallate (EGCG) as a nucleophilic reagent to attack C4 sites of subunits EGCG and epigallocatechin (EGC) of the proanthocyanidin from Chinese bayberry leaves in the presence of hydrochloric acid as a catalyst. Compared with prodelphinidin B9 gallates extracted and separated from materials such as tea leaves, and Chinese bayberry leaves, the prodelphinidin B9 gallate prepared by the method provided in the present disclosure has higher purity and yield, and can be directly used as a nutrient enhancer and a natural antioxidant in the field of food.

Abstract: A constant value method for detecting and evaluating internal leakage in a hydraulic cylinder and a detection device. The method comprises: step (1) measuring an accurate pressure drop value ?p of the internal leakage in the hydraulic cylinder; step (2), determining whether the detected hydraulic cylinder meets a standard: if the product of the accurate pressure drop value ?p of the internal leakage in the hydraulic cylinder and a corresponding hydraulic stroke L, is less than a standard parameter C for evaluating the internal leakage in the hydraulic cylinder, C = 4 ? QtK ? ? D 2 , the internal leakage in me hydraulic cylinder meets the standard. Otherwise, the internal leakage in the hydraulic cylinder does not meet the standard. The detection device comprises a motor, a hydraulic pump, a directional valve, a detected part, a pipeline disassembly joint and a pressure sensor.

Abstract: Embodiments of the present disclosure relate to method, device and computer program product for data backup. The method comprises: in response to receiving from a backup server a data stream to be backed up, dividing the data stream into a plurality of data segments; distributing the plurality of data segments to at least one computing node; in response to receiving an index of a corresponding data segment from a first computing node of the at least one computing node, looking up the index in a global index cache, the index being generated by the first computing node to uniquely identify the data segment, the global index cache storing indexes of data in a backup storage device; in response to the missing index in the global index cache, adding the index into the global index cache; and sending to the first computing node an indication to store the data segment in the backup storage device.

Abstract: Techniques for managing metadata storage units involve: in response to receiving, from a client, a request for allocating a target number of metadata storage units, determining a first number of available metadata storage units remaining in a metadata storage space of a storage system after the allocation is performed; and if the first number is not less than a reserved number, allocating the target number of metadata storage units from the metadata storage space for the client to use, wherein the reserved number is associated with a usage condition of the metadata storage units in the storage system. Accordingly, such techniques can effectively manage metadata and improve the performance of a system.

Abstract: The present disclosure describes techniques of performing machine unlearning in a recommendation model. An unlearning process of the recommendation model may be initiated in response to receiving a request for deleting a fraction of user data from any particular user. The recommendation model may be pre-trained to recommend content to users based at least in part on user data. Values of entries in a matrix corresponding to the fraction of user data may be configured as zero. The matrix may comprise entries denoting preferences of users with respect to content items. Confidence values associated with the fraction of user data may be configured as zero to block influence of the fraction of user data on performance of the recommendation model. The unlearning process may be implemented by performing a number of iterations until the recommendation model has converged.

Abstract: Techniques for storage management involve determining, in response to a detection that a disk changes from an unavailable state to an available state, at least one candidate storage unit associated with the disk; acquiring historical access information about the at least one candidate storage unit, the historical information comprising information related to a write request directed to the at least one candidate storage unit when the disk is in the unavailable state; determining a target storage unit from the at least one candidate storage unit based on the historical access information; and rebuilding the target storage unit. Such techniques may, in a low-cost manner, improve rebuilding efficiency and reliability of a storage system.

Abstract: Techniques manage a storage system. Along these lines, a failed storage device is detected among storage devices included in a resource pool of the storage system, and the storage devices belong to a first group and a second group in the resource pool respectively. An extent in the failed storage device assigned for building a stripe in the storage system is determined. A spare reserved extent is selected from respective reserved extents included in respective storage devices among the storage devices based on a mapping relation between the stripe and a plurality of extents in the stripe. The respective reserved extents are shared among the first group and the second group. Data in the extent are rebuilt to the selected spare reserved extent. A reserved storage area can be shared among various storage devices in the resource pool, so as to increase allocatable space in storage devices.

Abstract: Techniques for managing data blocks involve: generating, based on a first hash algorithm, a first fingerprint for a first block. The techniques further involve: if it is determined that there is a second fingerprint, in a fingerprint database, that is generated for a second block based on the first hash algorithm and matches the first fingerprint, determining whether there is a third fingerprint, in the fingerprint database, that is generated for the second block based on a second hash algorithm. The techniques further involve: if it is determined that the third fingerprint exists in the fingerprint database, generating a fourth fingerprint for the first block based on the second hash algorithm; and determining whether the first block and the second block are duplicate by comparing the third fingerprint and the fourth fingerprint. Such techniques can effectively reduce the overhead of identifying duplicate data blocks in data deduplication.

Abstract: Techniques perform storage management. The techniques involve: in response to a target request for a target redundant array of independent disks (RAID), determining that data in a first storage block associated with the target RAID needs to be moved or copied, wherein the target request includes one of the following: a restriping request, a type conversion request, or a rebalancing request; creating an intermediate RAID associated with an idle second storage block; and copying the data in the first storage block to a corresponding storage space in the intermediate RAID to write at least part of the data in the second storage block. Based on this mode, RAID restriping, type conversion, or rebalancing can be implemented efficiently.

Abstract: Embodiments of the present disclosure relate to methods, devices and computer program products for writing data in a disk array in a storage system. The storage system comprises a disk array. The method comprises: in response to receiving a write request to write new data to a data block in at least one disk array group in a degraded mode within a disk array, reading old data stored in the data block and old parity information stored in a parity block associated with the data block. The method further comprises: determining new parity information associated with the new data based on the old data, the old parity information and the new data. The method further comprises: writing the new data and the new parity information into at least one cache page provided by a cache component in the storage system, the at least one cache page being allocated in a persistent memory in the cache component.

Abstract: Techniques for managing a redundant array of independent disks (RAID) involve detecting an abnormality of a storage device in a RAID. The techniques further involve resetting the storage device in response to detecting the abnormality. The techniques further involve storing an address of a write operation for the RAID within a preset time period, so as to rebuild the RAID in the case that the storage device is recovered within the preset time period. Accordingly, temporary errors of the RAID can be efficiently handled, the number of downtime of the RAID caused by the storage device or the back end can be reduced, and computing resources and time required to rebuild the RAID can be significantly reduced.

Abstract: Techniques involve: determining a first group of storage disks, a use rate of each storage disk of the first group of storage disks exceeding a first threshold, the first group of storage disks comprising a first group of storage blocks corresponding to a first redundant array of independent storage disk (RAID); allocating a second group of storage blocks corresponding to a second RAID from a second group of storage disks, the second group of storage blocks having the same size as that of the first group of storage blocks, a use rate of each storage disk of the second group of storage disks being under a second threshold; moving data in the first group of storage blocks to the second group of storage blocks; and releasing the first group of storage blocks from the first group of storage disks. Thus, use rates of the storage disks become more balanced.

Abstract: A technique for managing a datapath of a data storage system includes receiving a request to access target data and creating a transaction that includes multiple datapath elements in a cache, where the datapath elements are used for accessing the target data. In response to detecting that one of the datapath elements is invalid, the technique further includes processing the transaction in a rescue mode. The rescue mode attempts to replace each invalid datapath element of the transaction with a valid version thereof obtained from elsewhere in the data storage system. The technique further includes committing the transaction as processed in the rescue mode.

Abstract: A method is used for tracking storage utilization in a storage system. An amount of physical storage space available for use on an appliance is determined. The amount of storage space consumed by each type of data being stored on the appliance is normalized. These normalized amounts are used to determine an amount of storage space on the appliance consumed by the data. When a percentage of storage space consumed on the appliance exceeds a threshold, an alert is generated.

Abstract: Techniques for managing a storage system involve flushing a target page in a cache device to a persistent storage device of the storage system. The techniques further involve releasing a resource storing a page descriptor of the target page to a resource pool. The resource pool is configured to provide resources to store page descriptors of pages to be flushed in the cache device. The techniques further involve: if it is determined that an auxiliary descriptor of the target page is located at a tail of a queue of auxiliary descriptors of the pages to be flushed, removing the auxiliary descriptor of the target page from the queue. The auxiliary descriptors of the pages to be flushed are configured to describe the page descriptors of the pages to be flushed. Accordingly, the page flushing performance of the storage system can be improved, thereby improving the input/output performance.

Abstract: A technique involves determining, in redundant array of independent disks (RAID) stripes, source slices for restriping, and allocating, from a reserved capacity for file system check (FSCK), destination slices for restriping. The technique further involves performing restriping for the RAID stripes by copying data in the source slices into the destination slices. Accordingly, using the reserved capacity for FSCK as the destination slices for restriping may mitigate the influence on an available capacity of a mapper during restriping, thereby improving the performance of a storage system.

Abstract: Techniques for managing a storage system involve: based on a degree of importance of data stored in a persistent storage device of the storage system, determining key data from the data, wherein a degree of importance of the key data is higher than a threshold degree; respectively identifying first data corresponding to the key data in a first cache of the storage system and second data corresponding to the key data in a second cache of the storage system as non-removable; and in response to corruption of the first data, repairing the first data using the second data in the second cache. Such techniques can avoid system shutdown caused by corruption of key data.

Abstract: Storage management techniques involve: acquiring target data in a target storage page in a memory; determining, based on the target data, check information and identification information associated with the target data, the check information being used to verify whether the target data is correct and the identification information being used to identify the target data; and determining, based on the identification information, storage information associated with the target data and the check information, the storage information indicating whether to store the target data and the check information to a persistent storage device. Therefore, the processing efficiency can be improved, and the input/output (I/O) performance can be improved.

Abstract: Techniques performed by a computing device of storing data in a data storage system are provided. A method includes (a) storing references to write commands within entries of a first chained hash table (CHT), the first CHT being pointed to by a first data structure representative of a logical disk; (b) keeping track of a load factor of the first CHT during operation; and (c) in response to determining that the load factor of the first CHT has transitioned outside of predetermined bounds: (1) creating a second CHT and a second data structure representative of the logical disk, the second CHT being pointed to by the second data structure; (2) linking the second data structure to the first data structure via a linked list; and (3) storing references to new write commands directed at the logical disk within entries of the second CHT rather than the first CHT.