A method of managing a data storage cache, comprising: providing a redundant cache comprising first and second caches associated with first and second storage volumes. One of the first and second storage volumes is an active, and one is a passive volume. A write request is received at one of the volumes. If the write request is received at the passive volume, it is forwarded to the active volume. It is determined whether the active volume is a low latency volume. If it is a low latency volume, it is determined whether data exists in the cache associated with the active volume which overlaps with data contained in the write request. If no data exists in that cache which overlaps with data contained in the write request, the write request is processed straight down to said active volume.

A multi-core processor having a first operation mode in which processors perform the same task and a second operation mode in which the processors perform different tasks includes first and second processors configured to write an operation mode value to a first register or second register when a function called in executed software requests the first or second operation mode, a manager configured to assign core IDs of the first and second processors according to the operation mode value stored in the first register or second register, and a reset controller configured to reset the first and second processors in response to the function, wherein the manager assigns the same core ID to the first and second processors when the operation mode value indicates the first operation mode, and allocates different core IDs to the first and second processors when the operation mode value indicates the second operation mode.

Techniques are described for processing multi-page write operations to maintain write level consistency. A multi-page write spanning multiple cache pages is directed to a target device and received on a first data storage system where writes to the target device are synchronously replicated to a second data storage system. On the first data storage system, each of the multiple cache pages may be synchronously replicated to the second data storage system. A lock on each of the cache pages is not released until an acknowledgement is received regarding successful replication of the cache page. On the second data storage system, requests to replicate the multiple cache pages containing write data of the multi-page write are received and processed using locks of corresponding cache pages on the second data storage system. Such techniques also handle concurrent reads and/or writes. Deadlock detection and resolution processing may be performed for concurrent writes.

A method, article of manufacture, and apparatus for backup operations. A read request is received for a data segment at a deduplicated storage system. The data segment is determined not to be in a data cache on the deduplicated storage system. A data segment reference for the data segment is determined to be in a data segment reference cache on the deduplicated storage system. The data segment is read from a persistent storage using the data segment reference.

A method of managing a data storage cache, comprising: providing a redundant cache comprising first and second caches associated with first and second storage volumes. One of the first and second storage volumes is an active, and one is a passive volume. A write request is received at one of the volumes. If the write request is received at the passive volume, it is forwarded to the active volume. It is determined whether the active volume is a low latency volume. If it is a low latency volume, it is determined whether data exists in the cache associated with the active volume which overlaps with data contained in the write request. If no data exists in that cache which overlaps with data contained in the write request, the write request is processed straight down to said active volume.

A storage system, maintains a cache and a non-volatile storage. Active tracks in the non-volatile storage are determined. The determined active tracks in the non-volatile storage are validated between the cache and the non-volatile storage during a warmstart recovery.

A storage system, maintains a cache and a non-volatile storage. Active tracks in the non-volatile storage are determined. The determined active tracks in the non-volatile storage are validated between the cache and the non-volatile storage during a warmstart recovery.

A technique for managing a cache in a data storage system includes creating metadata that associates cache pages with respective data objects and storing the metadata in a location accessible to a manager of the cache. Upon a failure in the cache, the cache manager checks the metadata to identify any data objects for which the cache stores dirty pages. The cache manager then coordinates with other system resources to take the identified data objects offline.

A cache or other cluster is configuration-aware such that initialization and changes to the underlying structure of the cluster can be dynamically updated for use by a client. A client may use a client driver as an intermediary that is responsible for managing the communication with the cluster. For example, a client driver may resolve an alias from a static configuration endpoint to a storage node. The client driver may request an initial configuration from the storage node and then update configuration from one or more storage nodes that store current configuration of the cluster.

Techniques for processing a read I/O operation that reads first content stored at a target logical address can include: determining, using the target logical address as a first key to index into a first cache, whether the first cache includes a first cache entry caching first metadata used to access a first physical storage location including the first content stored at the target logical address; responsive to determining the first cache includes the first cache entry, determining, using the first metadata as a second key to index into a second cache, whether the second cache includes a second cache entry caching the first content stored at the target logical address; and responsive to determining the second cache includes the second entry, returning the first content from the second entry of the second cache in response to the read I/O operation.