Abstract: Exemplary embodiments relate to cache replacement schemes. Incoming data may be sorted into buckets. When it comes time to replace information in the cache, an entire bucket may be eliminated or replaced at once. By sorting incoming data into the buckets and performing cache replacement on a bucket-by-bucket basis, cache fragmentation is reduced. Moreover, the buckets may be scored based on characteristics of the data in the buckets (e.g., whether a data item is cold archived, whether a customer has pinned the data item, or whether the customer has requested early eviction of the data item). By accounting for these metrics when the cache score is calculated, cache usage and hit rates may be improved. According to exemplary embodiments, scoring may be applied to entire buckets, or may be applied to individual cache items (e.g., for use as a cache replacement metric in a cache eviction scheme).

Abstract: Exemplary embodiments relate to cache replacement schemes. Incoming data may be sorted into buckets. When it comes time to replace information in the cache, an entire bucket may be eliminated or replaced at once. By sorting incoming data into the buckets and performing cache replacement on a bucket-by-bucket basis, cache fragmentation is reduced. Moreover, the buckets may be scored based on characteristics of the data in the buckets (e.g., whether a data item is cold archived, whether a customer has pinned the data item, or whether the customer has requested early eviction of the data item). By accounting for these metrics when the cache score is calculated, cache usage and hit rates may be improved. According to exemplary embodiments, scoring may be applied to entire buckets, or may be applied to individual cache items (e.g., for use as a cache replacement metric in a cache eviction scheme).

Abstract: Exemplary embodiments address the problem of disk fragmentation by using the heuristics of write operations to assign block sizes. As write requests are received, a storage system may register a size of the write request. Using the registered sizes, the storage system may identify one or more clusters of sizes at which write requests are particularly prevalent. The storage system may calculate a distribution or variance for block sizes centered on each cluster. The distribution or variance may be used to distribute the block sizes such that the block sizes change by a small amount in the vicinity of the cluster, and by a larger amount as the blocks move away from the center of the cluster. When it comes time to allocate new blocks, the clusters and distribution may be consulted to determine what sizes of blocks to allocate, and how many blocks of each size.

Abstract: An image-based backup backs up one or more snapshots of a volume without duplicating common data blocks. A backup engine receives a request to generate a backup image of a volume. In response to the request, the backup engine generates the backup image including data blocks and metadata describing attributes of the data blocks. The data blocks and the metadata arranged in the backup image in a same order as they were retrieved without imposing any additional ordering constraints on the data blocks and the metadata.

Abstract: Aspects of the present invention provide a disk-to-disk-to-tape backup method and system responsive to a combined backup request to backup a dataset to a backup disk according to a disk backup schedule and then to backup the dataset from the backup disk to a backup tape according to a tape backup schedule. The combined backup method completes a backup of the dataset to the backup disk and then to a backup tape device in accordance with a resolved schedule that considers potential conflicts between the schedules. To restore, aspects of the invention receive a request to restore a backup of the dataset from a backup-tape and the resolved schedule derived from the tape backup schedule and the disk backup schedule. The restoration verifies that a backup tape holds the target dataset by matching a combined backup identifier from the request against a corresponding combined backup identifier held in storage.

Abstract: Image-based data restoration restores an entire image of a volume or selective files. A restore engine receives a request to restore data from a backup image that includes a plurality of data blocks and metadata describing attributes of the data blocks. In response to the request, the restore engine determines a restore mode. If it is determined to be a logical restore mode, the restore engine restores a file by retrieving the metadata associated with the file and the data blocks that are pointed to by the metadata. If it is determined to be an image restore mode, the restore engine restores an entire image of the volume by using the data blocks in the backup image without using the metadata.