Abstract: Techniques involve: receiving, by a destination device, first input/output (I/O) requests from a source device, the first I/O requests having first logical block addresses (LBAs); writing data in the first I/O requests to a cache of the destination device; flushing the data from the cache to a storage disk of the destination device; recording a particular LBA in the destination device, the particular LBA corresponding to the last LBA to which the destination device is flushed; and sending the particular LBA from the destination device to the source device to enable clearing of journals before the particular LBA in the source device. Such techniques reduce the time spent on replicating data from the source device to the destination device to improve the user experience and reduce the wear and tear of the journal log disk in the destination device to prolong its service life.

Abstract: A technique manages solid state device (SSD) wear-level. The technique involves storing data on a plurality of SSDs. The technique further involves, based on storing the data on the plurality of SSDs, identifying a particular SSD of the plurality of SSDs as a target SSD. The technique further involves moving write-hot data to the particular SSD identified as the target SSD to increase writing workload on the particular SSD compared to respective writing workloads on other SSDs of the plurality of SSDs. Accordingly, the particular SSD wears out ahead of the other SSDs and avoids multiple SSD failures at the same time which otherwise could result in data unavailability (DU) and/or data loss (DL).

Abstract: Techniques for storing metadata involve: storing first metadata associated with a system operation in a volatile memory of a storage system while the storage system is in a startup stage. The storage system does not perform read/write requests of a client during the startup stage. Such techniques further involve: suspending the system operation of the storage system during the startup stage in response to determining that the intermediate persistent storage device has failed. Such techniques further involve: storing the first metadata in the volatile memory into the persistent storage device. Such techniques further involve: storing the first metadata into the intermediate persistent storage device in response to determining that the intermediate persistent storage device is available again. Accordingly, the risk of losing metadata when the storage device is powered down can be reduced.

Abstract: Techniques involve: receiving, by a destination device, first input/output (I/O) requests from a source device, the first I/O requests having first logical block addresses (LBAs); writing data in the first I/O requests to a cache of the destination device; flushing the data from the cache to a storage disk of the destination device; recording a particular LBA in the destination device, the particular LBA corresponding to the last LBA to which the destination device is flushed; and sending the particular LBA from the destination device to the source device to enable clearing of journals before the particular LBA in the source device. Such techniques reduce the time spent on replicating data from the source device to the destination device to improve the user experience and reduce the wear and tear of the journal log disk in the destination device to prolong its service life.

Abstract: A method, computer program product, and computing system for determining that one non-volatile random access memory (NVRAM) drive of a pair of NVRAM drives of a storage system is offline, thus defining an offline NVRAM drive and an online NVRAM drive. A virtual disk may be generated on a plurality of solid-state disks (SSDs) of the storage system. The contents of the online NVRAM drive may be copied to the virtual disk. The virtual disk may be exposed to the storage system as a representation of the offline NVRAM drive.

Abstract: Techniques for storing metadata involve: storing first metadata associated with a system operation in a volatile memory of a storage system while the storage system is in a startup stage. The storage system does not perform read/write requests of a client during the startup stage. Such techniques further involve: suspending the system operation of the storage system during the startup stage in response to determining that the intermediate persistent storage device has failed. Such techniques further involve: storing the first metadata in the volatile memory into the persistent storage device. Such techniques further involve: storing the first metadata into the intermediate persistent storage device in response to determining that the intermediate persistent storage device is available again. Accordingly, the risk of losing metadata when the storage device is powered down can be reduced.

Abstract: Techniques for storage management involve determining a plurality of storage units to be reconstructed on a group of disks, the plurality of storage units being distributed on different disks in the group of disks. Such techniques further involve selecting, based on the distribution of the plurality of storage units on the group of disks, a group of storage units from the plurality of storage units so that different storage units in the group of storage units are distributed on different disks. Such techniques further involve performing concurrent reconstruction on the group of storage units.

Abstract: A method, computer program product, and computing system for determining that one non-volatile random access memory (NVRAM) drive of a pair of NVRAM drives of a storage system is offline, thus defining an offline NVRAM drive and an online NVRAM drive. A virtual disk may be generated on a plurality of solid-state disks (SSDs) of the storage system. The contents of the online NVRAM drive may be copied to the virtual disk. The virtual disk may be exposed to the storage system as a representation of the offline NVRAM drive.

Abstract: A technique for storage management involves: determining multiple source disk slices from a storage array that provides redundant storage, a current disk group where each of the multiple source disk slices is located being different from a target disk group where the source disk slice is specified to be located; determining multiple destination disk slices from the target disk group based on the multiple source disk slices, the multiple destination disk slices being used to replace the multiple source disk slices; and causing data to be moved to the multiple destination disk slices from the multiple source disk slices. Accordingly, such a technique may improve the reliability of a storage system.

Abstract: Techniques for storage management involve determining a plurality of storage units to be reconstructed on a group of disks, the plurality of storage units being distributed on different disks in the group of disks. Such techniques further involve selecting, based on the distribution of the plurality of storage units on the group of disks, a group of storage units from the plurality of storage units so that different storage units in the group of storage units are distributed on different disks. Such techniques further involve performing concurrent reconstruction on the group of storage units.

Abstract: Techniques for data recovery involve: reading target data corresponding to a first logical block from a first data block of a stripe of a RAID system, the target data being a compressed version of data in the first logical block; in accordance with a determination that an error occurs in the target data, reading data from a plurality of second data blocks of the stripe and first parity information from a first parity block of the stripe; comparing respective checksums of the data read from the plurality of second data blocks with a first predetermined checksum and a checksum of the first parity information with a second predetermined checksum; and determining recoverability of the target data based on a result of the comparison. Accordingly, it is possible to simplify the data recovery process, reduce the calculation and time costs in the data recovery, and improve the data recovery efficiency.

Abstract: In creating an extent array in a storage system, in response to receiving a request to generate an extent array using idle extents in storage devices, a width of an extent stripe is determined, and a size of the extent array is designated by the storage system. A first extent group and a second extent group are respectively selected from the storage devices based on the width to form a first extent stripe and a second extent stripe, and a first extent at a given position in the first extent group and a second extent at a given position in the second extent group are respectively located in different storage devices. Based on the first extent stripe and the second extent stripe, an address mapping representing the extent array is generated. The address mapping includes association between extent identifiers of extents and extent indexes of the extents.

Abstract: In response to receiving a read request for target data, an external address of the target data is obtained from the read request, which is an address unmapped to a storage system; hit information of the target data in cache of the storage system is determined based on the external address; and based on the hit information, an address from the external address and an internal address for providing the target data is determined. The internal address is determined based on the external address and a mapping relationship. Therefore, it can shorten the data access path, accelerate the responding speed for the data access request, and allow the cache to prefetch the data more efficiently.

Abstract: A technique maintains availability of a non-volatile cache. The technique involves arranging a plurality of non-volatile random-access memory (NVRAM) drives into initial drive sets that form the non-volatile cache. The technique further involves detecting a failed initial drive set among the initial drive sets. The plurality of NVRAM drives now includes failed NVRAM drives that belong to the failed initial drive set and remaining non-failed NVRAM drives. The technique further involves, in response to detecting the failed initial drive set, re arranging the remaining non-failed NVRAM drives of the plurality of NVRAM drives into new drive sets that form the non-volatile cache.

Abstract: Techniques involve: determining, according to a determination that a performance level of a target storage unit is lower than a threshold level, whether idle disk slices that can be used for reconstructing malfunctioning disk slices in the target storage unit exist in a slice pool; determining a priority of the target storage unit according to a determination that the idle disk slices do not exist; and selecting replacing disk slices for reconstructing the malfunctioning disk slices from available storage units based at least in part on the priority, wherein the available storage units have performance levels not lower than the threshold level. In this way, data loss due to the off-line of storage units is prevented; and meanwhile, the performance of the entire storage system can be globally stabilized.

Abstract: A technique maintains availability of a non-volatile cache. The technique involves arranging a plurality of non-volatile random-access memory (NVRAM) drives into initial drive sets that form the non-volatile cache. The technique further involves detecting a failed initial drive set among the initial drive sets. The plurality of NVRAM drives now includes failed NVRAM drives that belong to the failed initial drive set and remaining non-failed NVRAM drives. The technique further involves, in response to detecting the failed initial drive set, re arranging the remaining non-failed NVRAM drives of the plurality of NVRAM drives into new drive sets that form the non-volatile cache.

Abstract: Techniques involve managing a storage system. In accordance with the techniques, a plurality of copies of metadata of the storage system are read from a plurality of storage devices in a resource pool of the storage system. The resource pool includes a first number of storage devices, and the metadata describes configuration information of the storage system. A second number of copies are selected from the plurality of copies based on version information in the plurality of copies, where the second number of copies comprises the metadata in the same version. It is determined whether a relation between the first number and the second number satisfies a predetermined condition. The second number of copies are identified as trusted metadata based on determining the relation satisfies the predetermined condition. With the foregoing example implementation, the metadata in the storage system may be managed with higher reliability.

Abstract: A storage management technique involves: receiving from a requesting node a write request for writing target data into a first target storage space in a redundant array of independent disks (RAID); if a storage device associated with the first target storage space does not fail, acquiring first data stored in the first target storage space and a first parity value corresponding to the requesting node and stored in a parity storage space; determining a target parity value based on the target data, the first data, and the first parity value; and updating a stripe with the target data and the target parity value. Accordingly, locks caused by updating the parity value can be avoided, so that different nodes can perform parallel write to different storage spaces in the same stripe in the RAID.

Abstract: A storage management technique involves: receiving from a requesting node a write request for writing target data into a first target storage space in a redundant array of independent disks (RAID); if a storage device associated with the first target storage space does not fail, acquiring first data stored in the first target storage space and a first parity value corresponding to the requesting node and stored in a parity storage space; determining a target parity value based on the target data, the first data, and the first parity value; and updating a stripe with the target data and the target parity value. Accordingly, locks caused by updating the parity value can be avoided, so that different nodes can perform parallel write to different storage spaces in the same stripe in the RAID.

Abstract: In creating an extent array in a storage system, in response to receiving a request to generate an extent array using idle extents in storage devices, a width of an extent stripe is determined, and a size of the extent array is designated by the storage system. A first extent group and a second extent group are respectively selected from the storage devices based on the width to form a first extent stripe and a second extent stripe, and a first extent at a given position in the first extent group and a second extent at a given position in the second extent group are respectively located in different storage devices. Based on the first extent stripe and the second extent stripe, an address mapping representing the extent array is generated. The address mapping includes association between extent identifiers of extents and extent indexes of the extents.