Abstract: Techniques herein are for creating a database snapshot by creating a sparse database. A method involves receiving a creation request to create a sparse database. The creation request has an identity of a parent database. The creation request is processed to create a sparse database. The sparse database has the identity of the parent database. The sparse database does not contain data copied from the parent database. A write request to write data into the sparse database is received. The write request is processed by writing the data into the sparse database. The parent database does not receive the data.

Abstract: Techniques herein are for accessing non-materialized blocks of a sparse file. A method involves a storage system receiving a storage command to access a sparse file. A combined content of a set of materialized blocks and a header that identifies one or more non-materialized blocks is assembled. The combined content does not comprise a content of the one or more non-materialized blocks. Responsive to the assembling, the combined content is transferred between the storage system and a computer system.

Abstract: Dirty data in a storage device is made current through rapid re-silvering, which uses a mirrored and up-to-date version of the dirty data from another storage device to recover the data. Because under rapid re-silvering cache metadata in volatile memory survives the failure of the cache, the cache metadata is used to determine which subset of data from the other storage device needs to be copied to the storage device being re-silvered. During re-silvering, cache metadata is used to determine which I/O requests from clients are requests for data that is not stale.

Abstract: A method and system for fast file initialization is provided. An initialization request to create or extend a file is received. The initialization request comprises or identifies file template metadata. A set of allocation units are allocated, the set of allocation units comprising at least one allocation unit for the file on a primary storage medium without initializing at least a portion of the file on the primary storage medium. The file template metadata is stored in a cache. The cache resides in at least one of volatile memory and persistent flash storage. A second request is received corresponding to a particular allocation unit of the set of allocation units. Particular file template metadata associated with the particular allocation unit is obtained. In response to the second request, at least a portion of a new allocation unit is generated.

Abstract: No-loss rapid recovery performs resynchronization efficiently while concurrently allowing availability to mirrored data on the storage device. No-loss rapid recovery has two stages and involves storage devices that have both a non-volatile cache and primary storage and that operate as mirror buddies. The first stage is referred to herein as the buddy-retention stage. During the buddy-retention stage, writes to mirrored data are not performed on the offline mirror buddy but are performed on the online mirror buddy. The mirrored data changed in the online mirrored buddy is retained in the non-volatile cache of the retention buddy. The next stage is referred to herein as the rapid resynchronization stage. In this stage, the changed mirrored data retained by the retention buddy for no-loss rapid recovery is used to resynchronize the offline buddy. The storage device is resynchronized using the changed mirrored data retained in the cache of the mirror buddy.

Abstract: Dirty data in a storage device is made current through rapid re-silvering, which uses a mirrored and up-to-date version of the dirty data from another storage device to recover the data. Because under rapid re-silvering cache metadata in volatile memory survives the failure of the cache, the cache metadata is used to determine which subset of data from the other storage device needs to be copied to the storage device being re-silvered. During re-silvering, cache metadata is used to determine which I/O requests from clients are requests for data that is not stale.