A method is disclosed for recovering data, the method comprising: retrieving a mapping structure associated with a volume in a storage system, the mapping structure including a plurality of entries, each entry including a respective short hash digest of a data block stored in the volume and an identifier of a location where the data block is stored; generating a plurality of long hash digests, each of the long hash digests being generated based on a different one of a plurality of data blocks that are stored in the storage system; comparing each of the long hash digests to a short hash digest of a missing data block, and adding the long hash digest to a candidate list when the long hash digest matches the short hash digest of the missing data block; generating a filtered candidate based on the candidate list; and recovering the missing data.

Provided are a method and an apparatus for managing a page cache in a virtualization service and a method for managing a page cache in a virtualization service according to an exemplary embodiment of the present disclosure includes: comparing a weight value of a container and a weight variable of a page possessed by a process operated by the container in the virtualization service with each other, changing the weight variable of the page based on a comparison result, and managing pages of the page cache using the changed weight variable of the page.

According to some embodiments, a backup storage system receives a request from a client at a storage system for accessing data segments. For each of a first groups of the data segments requested that are stored in a solid state device (SSD) cache, the system requests a first batch job for each of the first groups to retrieve the first groups of the data segments from the SSD cache via a first set of input/output (IO) threads. For each of a second groups of the data segments requested that are not stored in the SSD cache, the system requests a second batch job for each of the second groups to retrieve the second groups of the data segments from storage units of the storage system via a second set of input/output (IO) threads. The system assembles received segments and returns them to the client altogether.

A method is disclosed for recovering data, the method comprising: retrieving a mapping structure associated with a volume in a storage system, the mapping structure including a plurality of entries, each entry including a respective short hash digest of a data block stored in the volume and an identifier of a location where the data block is stored; generating a plurality of long hash digests, each of the long hash digests being generated based on a different one of a plurality of data blocks that are stored in the storage system; comparing each of the long hash digests to a short hash digest of a missing data block, and adding the long hash digest to a candidate list when the long hash digest matches the short hash digest of the missing data block; generating a filtered candidate based on the candidate list; and recovering the missing data.

Storage system management is provided. Metadata in a first version at a first time point of the storage system is obtained, here the metadata in the first version describes reference relations between at least one data block in a chunk included in the storage system and at least one object stored in the storage system at the first time point. Metadata in a second version at a second time point of the storage system is obtained, the second time point being after the first time point. The chunk included in the storage system is managed based on a determined difference between the metadata in the first version and the metadata in the second version. By means of the technical solution of the present disclosure, chunks in the storage system may be managed more effectively, and the chunk reclaiming efficiency may be increased.

Techniques perform I/O management. The techniques involve: in response to receiving an I/O request for a redundant array of independent disks (RAID), placing the I/O request in a corresponding waiting queue based on a stripe related to the I/O request in the RAID; and in response to the I/O request being granted to process, executing the I/O request based on storage of data of the stripe in a cache memory. Accordingly, by using the cache mechanism for the stripes, the I/O processing efficiency is improved and the user experience is enhanced. Moreover, the count of access to the RAID is reduced, the bandwidth for the backend access is saved and the system performance is improved.

A memory page management method is provided. The method includes receiving a state-change notification corresponding to a state-change page, and grouping the state-change page from a list to which the state-change page belongs into a keep list or an adaptive LRU list of an adaptive adjusting list according to the state-change notification; receiving an access command from a CPU to perform an access operation to target page data corresponding to a target page; determining that a cache hit state is a hit state or a miss state according to a target NVM page address corresponding to the target page, and grouping the target page into the adaptive LRU list according to the cache hit state; and searching the adaptive page list according to the target NVM page address to obtain a target DRAM page address to complete the access command corresponding to the target page data.

In accordance with one implementation, a method for mitigating cache transfer time entails reading data into memory from at least two consecutive elliptical data tracks in a main store region of data storage and writing the data read from the at least two consecutive elliptical data tracks to a spiral data track within a cache storage region.

An aspect of cache recovery includes transmitting entries of a write cache (WC) journal (entries) to all nodes and, for each node, recovering the entries, detecting entries with a logical address owned by the node, and performing a recovery operation. The operation includes for each entry, and upon determining the node owns the A2N slice: if the A2N slice has been continuously owned (CO) by the node, and the entry is not owned by the node, marking the entry as WC remote and entry updates are requested from a remote WC owner; if the A2N slice has not been CO by the node, and the entry is not owned by the node, maintaining the entry and continuing write flow operations, marking the entry as WC remote and all entry updates are requested from the remote WC owner and inserting the entry to a recovery list.

An access request processing apparatus comprises, a processor determines an object cache page according to a write request when receiving the write request. After determining that the NVM stores a log chain of the object cache page, the processor inserts, into the log chain of the object cache page, a second data node recording information about a second log data chunk. The log chain already includes a first data node recording information about the first log data chunk. The second log data chunk is at least partial to-be-written data of the write request. Then, the processor sets, in the first data node, data that is in the first log data chunk and that overlaps the second log data chunk to invalid data.