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: A protocol for processing write operations can include recording each write operation in a log using a PDESC (page descriptor)-PB (page block) pair. The log entry for the write operation can be included in a container of logged writes. In a dual node system, the protocol when processing the write operation, that writes first data, can include incrementing a corresponding one of two counters of the container, where the corresponding counter is associated with one of the system's nodes which received the write operation and and caches the first data. Each container can be associated with an logical block address (LBA) range of a logical device, where logged writes that write to target addresses in the particular LBA range are included in the container. Nodes can independently determine flush ownership using the container's counters and can flush containers based on the flush ownership.

Abstract: A protocol for processing write operations can include recording each write operation in a log using a PDESC (page descriptor)-PB (page block) pair. The log entry for the write operation can be included in a container of logged writes. In a dual node system, the protocol when processing the write operation, that writes first data, can include incrementing a corresponding one of two counters of the container, where the corresponding counter is associated with one of the system's nodes which received the write operation and and caches the first data. Each container can be associated with an logical block address (LBA) range of a logical device, where logged writes that write to target addresses in the particular LBA range are included in the container. Nodes can independently determine flush ownership using the container's counters and can flush containers based on the flush ownership.

Abstract: Techniques described herein coordinate inline deduplication among nodes in a storage system. The method includes storing, in a page descriptor ring on a node, data and a fingerprint associated with the data in an entry. The method includes determining that a flushing work set (FWS) has been frozen. The node identifies, in the page descriptor ring, entries associated with the frozen FWS and having fingerprints with a parity associated with the node. The node deduplicates the entries based on a fingerprint database on the node. The node synchronizes deduplication of the frozen FWS with a peer node, so as to receive deduplication results concerning entries having fingerprints with a parity associated with the peer node. The node replaces entries in the page descriptor ring with the deduplication results from the peer node, and flushes entries in the frozen FWS to a storage device.

Abstract: Techniques described herein coordinate inline deduplication among nodes in a storage system. The method includes storing, in a page descriptor ring on a node, data and a fingerprint associated with the data in an entry. The method includes determining that a flushing work set (FWS) has been frozen. The node identifies, in the page descriptor ring, entries associated with the frozen FWS and having fingerprints with a parity associated with the node. The node deduplicates the entries based on a fingerprint database on the node. The node synchronizes deduplication of the frozen FWS with a peer node, so as to receive deduplication results concerning entries having fingerprints with a parity associated with the peer node. The node replaces entries in the page descriptor ring with the deduplication results from the peer node, and flushes entries in the frozen FWS to a storage device.

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: 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: Techniques involve determining a first slice distribution used to build first storage units in a first pool; in response to a determination that the first pool is expanded to a second pool, determining, at least based on a sum of the slices having been used to build the first storage units, a second slice distribution of updated slices used to build the first storage units in the second pool; determining, based on the first distribution and the second distribution, a first available number of slices and a second available number of slices available for building second storage units in the second pool, the second storage units being different from the first storage units; and determining, at least based on the first available number and the second available number, the number of the second storage units allowed to be built. Accordingly, available capacity allowed for building can be accurately estimated.

Abstract: The present disclosure relates to a method, a device, and a computer program product for managing a storage system. The storage system includes a first control node, a second control node, and a persistent storage device, the first control node being in an activated state, and the second control node being in a state of transfer from a non-activated state to an activated state. A method includes: loading a first list of page descriptors of the storage system to the second control node to generate a second list of page descriptors at the second control node, the first list including a portion of multiple page descriptors of the storage system that has been modified but has not been flushed to the persistent storage device; receiving a synchronization message from the first control node that indicates that the first list has been modified by the first control node; and updating the second list at the second control node based on the synchronization message.

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, thereby optimizing system performance.

Abstract: Data access techniques involve: determining whether there is a copy operation that is being performed from a first LU to a second LU in response to receiving a write operation request for a first data block in the first logic unit (LU); detecting a copy status of data in the first data block in response to determining that there is the copy operation that is being performed; and determining a processing strategy of the write operation request during execution of the copy operation based on the copy status.

Abstract: A technique involves: in response to receiving a request to write data to a storage device, acquiring metadata of a redundant array of independent disks (RAID) extent that is associated with the request to write data, the RAID extent being built based on disk slices comprised in a plurality of disks of the storage device; determining, based on the metadata, a disk slice of data write-enabled RAID extent to write the data; and copying an identification and a degradation number into a metadata page associated with a mapper for data recovery, the identification and degradation number being comprised in the metadata and associated with the data write-enabled RAID extent, the mapper being used to map a physical space and a virtual logical space, and the degradation number indicating the number of times that the disk slice comprised in the RAID extent changes from being normal to being degraded.

Abstract: A method and system for managing a buffer device in a storage system. The method comprising determining a first priority for a first queue included in the buffer device, the first queue comprising at least one data page associated with a first storage device in the storage system; in at least one round, in response to the first priority not satisfying a first predetermined condition, updating the first priority according to a first updating rule, the first updating rule making the updated first priority much closer to the first predetermined condition than the first priority; and in response to the first priority satisfying the first predetermined condition, flushing data in a data page in the first queue to the first storage device.

Abstract: The present disclosure relates to a method, a device, and a computer program product for managing a storage system. The storage system includes a first control node, a second control node, and a persistent storage device, the first control node being in an activated state, and the second control node being in a state of transfer from a non-activated state to an activated state. A method includes: loading a first list of page descriptors of the storage system to the second control node to generate a second list of page descriptors at the second control node, the first list including a portion of multiple page descriptors of the storage system that has been modified but has not been flushed to the persistent storage device; receiving a synchronization message from the first control node that indicates that the first list has been modified by the first control node; and updating the second list at the second control node based on the synchronization message.

Abstract: A method, computer program product, and computing system for receiving one or more IO requests at a cache system for storing content in a storage array. A maximum number of concurrent backend IO requests may be associated with the storage array based upon, at least in part, a change in size of the storage array. The one or more TO requests may be flushed to the storage array via one or more backend IO requests from the cache system based upon, at least in part, the maximum number of concurrent backend IO requests associated with the storage array.

Abstract: Techniques manage a disk array. Such techniques involve determining, from one or more disk arrays constructed based on a plurality of disks, a target disk array to be restriped, the target disk array being associated with disk slices on different disks and including a stripe to be reconstructed, the stripe including extents located in the disk slices; determining, from the disk slices, a first disk slice on which data migration is to be performed, a first extent of the extents being located in the first disk slice; allocating, on the plurality of disks, a second disk slice for storing data from the first disk slice; and reconstructing the stripe by migrating data from the first extent of the first disk slice into the second disk slice. Such techniques significantly reduce the number of input/output operations during stripe reconstruction while avoiding waste of storage space.

Abstract: Techniques provide storage management. Such techniques involve storing cache data of a buffer memory corresponding to a storage disk group into a standby disk based on a determination that the number of disks in a first disk set in the storage disk group is less than a threshold number of disks. The techniques further involve adjusting at least one disk in a second disk set to the first disk set so that the number of disks in the adjusted first disk set and the number of disks in the adjusted second disk set are both greater than or equal to the threshold number of disks. The techniques further involve loading a first part of data in the standby disk into the adjusted first disk set. In addition, the techniques further involve loading a second part of data in the standby disk into the adjusted second disk set.

Abstract: Techniques process and manage a storage unit access. In accordance with such a technique, a data access request which is from a host system and for a first storage unit in the first storage system is received, wherein the first storage unit is a secondary storage unit; and the data access request is forwarded to a second storage unit in a second storage system associated with the first storage unit via a redirection link from the first storage system to the second storage system, wherein the second storage unit is a primary storage unit. Through such techniques, the host system can be allowed to send a data access request for the secondary storage unit, so that the host system does not need to resend the data access request, thereby reducing delay and interruption caused by such requests.

Abstract: Techniques manage metadata. Such techniques involve: in response to receiving a request for accessing metadata in a first page, determining, from a plurality of storage units including pages for storing metadata, a storage unit where the first page is located, the plurality of storage units including a first storage unit and a second storage unit, an access speed of the second storage unit exceeding an access speed of the first storage unit; accessing, from the determined storage unit, the first page for metadata; in response to the first page being accessed from the first storage unit, determining whether hotness of the first page exceeds a threshold level; and in response to the hotness of the first page exceeding the threshold level, transferring the first page from the first storage unit to the second storage unit. Accordingly, such techniques can improve the efficiency for accessing the metadata.

Abstract: The present invention discloses a method and device for managing a storage system. Specifically, in one embodiment of the present invention, there is proposed a method for managing a storage system, the storage system comprising a buffer device and a plurality of storage devices. The method comprises: receiving an access request with respect to the storage system; determining a storage device among the plurality of storage devices has been failed; and in response to the access request being an access request with respect to the failed storage device, serving the access request with data in the buffer device so as to reduce internal data access in the storage system. In one embodiment of the present invention, there is proposed a device for managing a storage system.