Abstract: A method, computer program product, and computer system for maintaining a back pointer from a physical layer block (PLB) to a virtual layer block (VLB) in a multi-level hierarchical file system. A generation number may be maintained in the VLB, wherein the generation number may indicate when data is moved from the PLB to another PLB. An object may be reconstructed in the multi-level hierarchical file system based upon, at least in part, at least one of the back pointer and the generation number.

Abstract: A method, computer program product, and computer system for setting a preferred alignment value to a size of an address space mapped by one or more root pages. An allocation request may be received for the address space. A binary buddy allocation scheme may be executed to allocate an extent for the allocation request based upon, at least in part, the preferred alignment value.

Abstract: An apparatus comprises a processing device configured to generate a tree structure characterizing relationships between storage objects in a storage system represented as logical page nodes specifying respective logical page addresses, arrays of pointers to other logical page addresses, snapshot group identifiers, and logical extent offsets. The processing device is also configured to traverse the generated tree structure to identify (i) a given logical page node specifying a given logical page address, snapshot group identifier and logical extent offset from a query and (ii) other ones of the logical page nodes that specify the given snapshot group identifier and logical extent offset and comprise a pointer to the given logical page address in its associated array of pointers. The processing device is further configured to provide a response to the query specifying the given logical page node and the identified other ones of the logical page nodes.

Abstract: An apparatus comprises a processing device configured to identify faults associated with a logical address space in a fault domain of a storage system, the faults specifying fault reason codes and metadata types for logical pages in the logical address space associated with the faults. The processing device is also configured to determine a fault summary characterizing impact of the faults in the fault domain of the storage system, the fault summary being based on aggregating fault scores assigned to the fault reason codes and the metadata types specified in the faults. The processing device is further configured to generate a recommendation on whether to initiate recovery of the fault domain of the storage system based on the fault summary, and to initiate recovery of the fault domain of the storage system based on the generated recommendation.

Abstract: An apparatus comprises a processing device configured to determine that an entry of a first data structure comprises an indication that a link between a first logical page and a second logical page is broken and to determine that a first address pointed to by the first logical page and a second address pointed to by the second logical page match. The processing device is further configured to determine that the first logical page corresponds to the second logical page based at least in part on the determination that the first address and the second address match and to add an indication of a third address that corresponds to the first logical page to an entry associated with the second logical page.

Abstract: An apparatus includes a processing device configured to generate log records each representing a pointer from a leaf page in a logical address space of a storage system to a virtual block address and comprising a leaf page address of the leaf page. The processing device is also configured to identifying a subset of the log records representing pointers to a given virtual block address to determine a first reference count, and to determine whether the first reference count is different than a second reference count obtained from a given virtual entry of a given virtual block structure that corresponds to the given virtual block address. The processing device is further configured, responsive to determining that the first and second reference counts are different, to modify pointers to the given virtual block address in leaf pages with associated leaf page addresses in the identified subset of the log records.

Abstract: An apparatus comprises a processing device configured to determine that an entry of a first data structure comprises an indication that a link between a first logical page and a second logical page is broken and to determine that a first address pointed to by the first logical page and a second address pointed to by the second logical page match. The processing device is further configured to determine that the first logical page corresponds to the second logical page based at least in part on the determination that the first address and the second address match and to add an indication of a third address that corresponds to the first logical page to an entry associated with the second logical page.

Abstract: An apparatus comprises a processing device configured to identify faults associated with a logical address space in a fault domain of a storage system, the faults specifying fault reason codes and metadata types for logical pages in the logical address space associated with the faults. The processing device is also configured to determine a fault summary characterizing impact of the faults in the fault domain of the storage system, the fault summary being based on aggregating fault scores assigned to the fault reason codes and the metadata types specified in the faults. The processing device is further configured to generate a recommendation on whether to initiate recovery of the fault domain of the storage system based on the fault summary, and to initiate recovery of the fault domain of the storage system based on the generated recommendation.

Abstract: An apparatus includes a processing device configured to generate log records each representing a pointer from a leaf page in a logical address space of a storage system to a virtual block address and comprising a leaf page address of the leaf page. The processing device is also configured to identifying a subset of the log records representing pointers to a given virtual block address to determine a first reference count, and to determine whether the first reference count is different than a second reference count obtained from a given virtual entry of a given virtual block structure that corresponds to the given virtual block address. The processing device is further configured, responsive to determining that the first and second reference counts are different, to modify pointers to the given virtual block address in leaf pages with associated leaf page addresses in the identified subset of the log records.

Abstract: An apparatus comprises a processing device configured to generate a tree structure characterizing relationships between storage objects in a storage system represented as logical page nodes specifying respective logical page addresses, arrays of pointers to other logical page addresses, snapshot group identifiers, and logical extent offsets. The processing device is also configured to traverse the generated tree structure to identify (i) a given logical page node specifying a given logical page address, snapshot group identifier and logical extent offset from a query and (ii) other ones of the logical page nodes that specify the given snapshot group identifier and logical extent offset and comprise a pointer to the given logical page address in its associated array of pointers. The processing device is further configured to provide a response to the query specifying the given logical page node and the identified other ones of the logical page nodes.

Abstract: An apparatus comprises a processing device configured to determine that a first data structure comprises an indication that a first logical page is an orphan and to obtain the first logical page based at least in part on the determination. The processing device is configured to identify a pointer to a second logical page from a second data structure of the first logical page and to determine a data offset that corresponds to the pointer. The processing device is configured to determine a snapshot group that corresponds to the first logical page and to identify a candidate logical page based at least in part on the data offset, the snapshot group and the pointer. The processing device is configured to determine that the candidate logical page is a match for the first logical page and to link the candidate logical page and the first logical page together.

Abstract: An apparatus comprises a processing device configured to obtain a first logical page and to obtain a first namespace address corresponding to a second logical page from the first logical page. The processing device is further configured to obtain the second logical page based at least in part on the first namespace address and to identify a given entry of a plurality of entries of the second logical page based at least in part on index information contained in the first logical page. The processing device is further configured to determine that the given entry comprises data other than a second namespace address corresponding to the first logical page and to add the second namespace address corresponding to the first logical page to the given entry based at least in part on the determination that the given entry comprises data other than the second namespace address.

Abstract: A method, computer program product, and computer system for maintaining a back pointer from a physical layer block (PLB) to a virtual layer block (VLB) in a multi-level hierarchical file system. A generation number may be maintained in the VLB, wherein the generation number may indicate when data is moved from the PLB to another PLB. An object may be reconstructed in the multi-level hierarchical file system based upon, at least in part, at least one of the back pointer and the generation number.

Abstract: A method, computer program product, and computer system for setting a preferred alignment value to a size of an address space mapped by one or more root pages. An allocation request may be received for the address space. A binary buddy allocation scheme may be executed to allocate an extent for the allocation request based upon, at least in part, the preferred alignment value.

Abstract: A method is used in managing file system checking in file systems. Metadata of a file system is evaluated upon receiving a request to perform file system checking on the file system. Based on the evaluation, determination is made as to whether file system checking has been performed previously on the file system. Based on the determination, file system checking is performed on the file system.

Abstract: A method is used in recovering duplicate blocks in file systems. A duplicate file system block is detected in a file system. The duplicate file system block is referred by a first inode associated with a first file of the file system and a second inode associated with a second file of the file system. Metadata of the duplicate file system block is evaluated. Based on the evaluation, a set of inodes in the file system is determined. Each inode of the set of inodes refer to the duplicate file system block. Based on the determination, the set of inodes is updated.

Abstract: A method is used in recovering file system blocks of file systems. A first read error is encountered upon reading a file system block of a file system. The file system block includes a first set of chunks. A second read error is encountered upon reading a duplicate copy of the file system block. The duplicate copy of the file system block includes a second set of chunks. Each chunk of the first and second sets of chunks is evaluated. Based on the evaluation, the file system block is recovered.

Abstract: A method is used in analyzing mapping objects of file systems. Each mapping object of a set of mapping objects of files of a file system is analyzed by iterating over the set of mapping objects. A file is associated with a first mapping object of the set of mapping objects and a snapshot copy of the file is associated with a second mapping object of the set of mapping objects. The second mapping object shares a subset of a set of storage objects associated with the first mapping object. Information for each storage object of the set of storage objects associated with each mapping object of the set of mapping objects is stored. Based on the stored information, each storage object of the set of storage objects associated with each mapping object of the set of mapping objects is processed.

Abstract: A method is used in recovering files in data storage systems. A set of file system blocks of a file of a file system is identified. The set of file system blocks are associated with a portion of an inode of the file of the file system. Mapping information associated with the portion of the inode is missing references to the set of file system blocks. Metadata of each file system block of the set of file system blocks is evaluated. Based on the evaluation, the portion of the inode of the file is recovered by updating mapping information associated with the portion of the inode.