Abstract: Nodes in a storage system can autonomously ingest I/O requests and flush data to storage. First and second nodes determine a sequence separator, the sequence separator corresponding to an entry in a page descriptor ring that separates two flushing work sets (FWS). The first node receives an input/output (I/O) request and allocates a sequence identification (ID) number to the I/O request. The first node determines a FWS for the I/O request based on the sequence separator and the sequence ID number, and commits the I/O request using the sequence ID number. The I/O request and the sequence ID number are sent to the second node.

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: Nodes in a storage system can autonomously ingest I/O requests and flush data to storage. First and second nodes determine a sequence separator, the sequence separator corresponding to an entry in a page descriptor ring that separates two flushing work sets (FWS). The first node receives an input/output (I/O) request and allocates a sequence identification (ID) number to the I/O request. The first node determines a FWS for the I/O request based on the sequence separator and the sequence ID number, and commits the I/O request using the sequence ID number. The I/O request and the sequence ID number are sent to the second node.

Abstract: Nodes in a storage system can autonomously ingest I/O requests and flush data to storage. First and second nodes determine a sequence separator, the sequence separator corresponding to an entry in a page descriptor ring that separates two flushing work sets (FWS). The first node receives an input/output (I/O) request and allocates a sequence identification (ID) number to the I/O request. The first node determines a FWS for the I/O request based on the sequence separator and the sequence ID number, and commits the I/O request using the sequence ID number. The I/O request and the sequence ID number are sent to the second node.

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: 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: Nodes in a storage system can autonomously ingest I/O requests and flush data to storage. First and second nodes determine a sequence separator, the sequence separator corresponding to an entry in a page descriptor ring that separates two flushing work sets (FWS). The first node receives an input/output (I/O) request and allocates a sequence identification (ID) number to the I/O request. The first node determines a FWS for the I/O request based on the sequence separator and the sequence ID number, and commits the I/O request using the sequence ID number. The I/O request and the sequence ID number are sent to the second node.

Abstract: A method is used for uninterrupted data flushing in a storage system. A barrier in a page descriptor ring is determined to distinguish between a filling flushing work set (FWS) and a frozen FWS. A sequence number of an I/O request is compared to the barrier. A FWS corresponding to the I/O request is identified based on the comparison. The I/O request is committed to the identified FWS.

Abstract: A method is used for uninterrupted data flushing in a storage system. An input/output (I/O) request is received. A pointer for a filling flushing work set (FWS) is atomically switching. A copy of the pointer for the filling FWS is saved, and the counter associated with a FWS referenced by the saved copy of the pointer is incremented. The saved copy of the pointer and the pointer for the filling FWS are compared, and upon determining that the saved copy of the pointer and the pointer for the filling are FWS equal, the I/O request is committed to a page descriptor ring and the counter associated with the FWS referenced by the saved copy of the pointer is decremented.

Abstract: A method of validating metadata pages that map to user data in a data storage system is provided. The method includes (a) obtaining first information stored for a first metadata page and second information stored for a second metadata page, the first and second metadata pages having a relationship to each other within a hierarchy of metadata pages for accessing user data; (b) performing a consistency check between the first information and the second information, the consistency check producing a first result in response to the relationship being verified and a second result otherwise; and (c) in response to the consistency check yielding the second result, performing a corrective action to restore consistency between the first and second information. An apparatus, system, and computer program product for performing a similar method are also provided.

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 method is used for uninterrupted data flushing in a storage system. A barrier in a page descriptor ring is determined to distinguish between a filling flushing work set (FWS) and a frozen FWS. A sequence number of an I/O request is compared to the barrier. A FWS corresponding to the I/O request is identified based on the comparison. The I/O request is committed to the identified FWS.

Abstract: A method is used for uninterrupted data flushing in a storage system. An input/output (I/O) request is received. A pointer for a filling flushing work set (FWS) is atomically switching. A copy of the pointer for the filling FWS is saved, and the counter associated with a FWS referenced by the saved copy of the pointer is incremented. The saved copy of the pointer and the pointer for the filling FWS are compared, and upon determining that the saved copy of the pointer and the pointer for the filling are FWS equal, the I/O request is committed to a page descriptor ring and the counter associated with the FWS referenced by the saved copy of the pointer is decremented.

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: 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: Techniques involve: writing, when a first disk for dirty page storage has a failure, a first target page description generated by a first node and associated with a first set of target dirty pages of the first node and a second set of target dirty pages of a second node to a first page description storage layer for the first node in a second disk; writing a second target page description generated by the second node and associated with the first set of target dirty pages and the second set of target dirty pages to a second page description storage layer for the second node in the second disk; and restoring, when the failure has been eliminated, the first set of target dirty pages and the second set of target dirty pages in the first disk based on at least one of the descriptions.

Abstract: Techniques provide for managing data storage. The techniques involve in response to receiving a request for unmapping a logical storage unit associated with a first disk slice on a first physical disk and the first disk slice, determining information associated with the first disk slice; generating, based on the information, a first entry and a second entry corresponding to the first disk slice; adding the first entry into a queue of failed disk slices to enable data stored on the first disk slice to be cleared; and adding the second entry into a queue of free disk slices to enable the first disk slice to be mapped to a further logical storage unit. Accordingly, such techniques can remarkably improve the write I/O performance of the system and prolong the lifetime of the SSD.

Abstract: In a method of flushing cached data in a data storage system, instances of a working-set structure (WSS) are used over a succession of operating periods to organize cached data for storing to the persistent storage. In each operating period, leaf structures of the WSS are associated with respective address ranges of a specified size. Between operating periods, a structure-tuning operation is performed to adjust the specified size and thereby dynamically adjust a PD-to-leaf ratio of the WSS, including (1) comparing a last-period PD-to-leaf ratio to a predetermined ratio range, (2) when the ratio is below the predetermined ratio range, increasing the specified size for use in a next operating period, and (3) when ratio is above the predetermined ratio range, then decreasing the specified size for use in the next operating period.