The embodiments deal with files that are already present in a storage when mounting the storage in a file system and files created after the mounting as different groups. (Metadata of) the files is classified. The files are each divided into metadata (index) and a file main body and are recorded on different storage areas, that is, an index partition (IP) and a data partition (DP), associated with each other. This file system is effective in a storage format in which a new file is merely written and an already written file is not updated or deleted (for example, a tape medium used in the LTFS). The embodiments implement a WORM file system by rejecting a request to update or delete a file that is present at mounting as a WORM file and permitting update or deletion of a file that is created after mounting until the storage is unmounted.

When a WORM cartridge is formatted for Tape File System (LTFS) in advance, such as prior to shipment, Linear Tape File System Library Edition (LTFS LE) is expanded by software to reduce consumption of the index partition and to support elimination of the appending of unnecessary data. More specifically, instead of recording metadata in the index partition during normal unmounting, the metadata is recorded in separate local storage such as on hard disk drive (HDD), and the index partition is updated only when the cartridge is ejected from the library. In this way, the present invention is able to significantly reduce the frequency of index partition updates. Because an update occurs only when the user intentionally ejects a cartridge, overflow of the index partition before overflow of the data partition can be prevented.

A method and/or system for providing for write once read many (WORM) times from at least some addresses of a storage drive that is otherwise manufactured for multiple writes to individual addresses. In at least one embodiment, a WORM area(s) is defined by a START_LBA and an END_LBA and the method uses a HWM_LBA to determine whether a LBA in the WORM area has been written to previously and to prevent previously written to LBA(s) in the WORM area from being rewritten. In at least one embodiment where there are multiple WORM areas, each WORM area has its own respective START_LBA, END_LBA and HWM_LBA.

One or more techniques and/or systems are provided for performing host side deduplication. Host side deduplication may be performed upon writeable data within a write request received at a host computing device configured to access data stored by a storage server. The host side deduplication may be performed at the host computing device to determine whether the writeable data is already stored by the storage server based upon querying a host side cache comprising data stored by a storage server and/or a data structure comprising unique signatures of data stored by the storage server. If the writeable data is stored by the storage server, then a deduplication notification excluding the writeable data may be sent to the storage server, otherwise a write command comprising the writeable data may be sent. Accordingly, unnecessary network traffic of redundant data already stored by the storage server may be reduced.

One or more techniques and/or systems are provided for performing host side deduplication. Host side deduplication may be performed upon writeable data within a write request received at a host computing device configured to access data stored by a storage server. The host side deduplication may be performed at the host computing device to determine whether the writeable data is already stored by the storage server based upon querying a host side cache comprising data stored by a storage server and/or a data structure comprising unique signatures of data stored by the storage server. If the writeable data is stored by the storage server, then a deduplication notification excluding the writeable data may be sent to the storage server, otherwise a write command comprising the writeable data may be sent. Accordingly, unnecessary network traffic of redundant data already stored by the storage server may be reduced.

A system for write-once memory (WOM) code emulation of EEPROM-type devices includes, for example, a host processor for sending data words for storing in a WOM (Write-Only Memory) device. A host interface receives the data words for encoding by a WOM controller. An emulator programs the WOM-encoded data and an address identifier as an entry of the WOM device. The emulator overwrites previously programmed WOM-encoded data by searching entries of a current active page of a WOM device to locate a programmed WOM entry that includes the searched-for address identifier and the previously written WOM-encoded data word. When the previously written WOM-encoded word cannot be correctly overwritten, the contents of the second WOM-encoded word are stored in a new entry. When the current active page is substantially full, the new entry is stored a new page and the current active page is block-erased.

Systems and methods are described for performing an instant recovery of data associated with a locked snapshot. In various examples, the amount of time for performing a recovery of data associated with a locked snapshot is significantly reduced by making use of enhanced volume cloning functionality instead of making an actual copy of the data to be recovered. In one embodiment, the resulting volume clone representing the recovery volume is cleared of all data protection information (e.g., WORM flags and/or lock metafiles) that was previously used to protect the content from being changed when stored on the data protection volume so as allow the recovery volume to be used in read-write mode.

A data management system may support techniques for immutable storage of snapshot data entities, which may each include data corresponding to one or more snapshots, in a cloud environment. The data management system may determine respective retention periods and respective immutability periods for the snapshot data entities. The data management system may extend the respective immutability period for a first snapshot data entity based on the respective retention period for the first snapshot data entity being greater than or equal to a threshold duration. Additionally or alternatively, the data management system may maintain (refrain from extending) the respective immutability period for a second snapshot data entity based at least in part on the respective retention period for the second snapshot data entity being less than the threshold duration.

A data management system may support techniques for immutable storage of snapshot data entities, which may each include data corresponding to one or more snapshots, in a cloud environment. The data management system may determine respective retention periods and respective immutability periods for the snapshot data entities. The data management system may extend the respective immutability period for a first snapshot data entity based on the respective retention period for the first snapshot data entity being greater than or equal to a threshold duration. Additionally or alternatively, the data management system may maintain (refrain from extending) the respective immutability period for a second snapshot data entity based at least in part on the respective retention period for the second snapshot data entity being less than the threshold duration.

Systems and methods are described for performing an instant recovery of data associated with a locked snapshot. In various examples, a recovery of data associated with a locked snapshot is performed by making use of volume cloning functionality instead of making an actual copy of the data to be recovered. In one embodiment, the resulting volume clone representing the recovery volume is cleared of all data protection information (e.g., WORM flags and/or lock metafiles) that was previously used to protect the content from being changed when stored on the data protection volume so as allow the recovery volume to be used in read-write mode.