Abstract: A database manager maintains a database including information tracking a set of storage units and a set of storage appliances on which the storage units currently reside. At least a portion of the tracking information is cached in a server cache at a namespace redirection server. Some of the tracking information is cached in a set of client caches at a set of clients. A request to access a storage unit is received at a client. A lookup is made into a client cache at the client to find a storage appliance having the storage unit. A determination is made that there is a problem accessing the storage unit using the client cache. So, the namespace redirection server is queried for updated tracking information concerning a location of the storage unit. The client assists the namespace redirection server with management of the server cache.

Abstract: Providing cache updates in a multi-node system through a service component between a lower level component and a next higher level component by maintaining a ledger storing an incrementing number indicating a present state of the datasets in a cache of the lower level component. The service component receives a data request to the lower level component from the higher level component including an appended last entry number accessed by the higher level component. It determines if the appended last entry number matches a current entry number in the ledger for any requested dataset. No match indicates that some data in the higher level component cache is stale. It then sends updated information for the stale data to the higher level component. The higher level component invalidates its cache entries and updates the appended last entry number to match a current entry number in the ledger.

Abstract: Embodiments for providing cache updates in a hierarchical multi-node system, through a service component between a lower level component and a next higher level component by maintaining a ledger storing an incrementing entry number indicating a present state of the datasets in a cache of the lower level component. The service component receives a data request to the lower level component from the higher level component including an appended last entry number accessed by the higher level component, and determines if the appended last entry number matches a current entry number in the ledger for any requested dataset, wherein no match indicates that at least some data in the higher level component cache is stale. In which case, it sends updated data information for the stale data to the higher level component, while the higher level component invalidates its cache entries and updates the appended last entry number to match a current entry number in the ledger.

Abstract: Information is stored that maps storage units to a pool of data protection appliances on which the storage units reside. The stored information includes a set of Internet Protocol (IP) addresses through which each data protection appliance can be reached. A connection request is received from a client. The connection request includes an identification of a particular storage unit which the client seeks to access for a data protection job. The particular storage unit is looked up in the stored information to identify a particular data protection appliance on which the particular storage unit currently resides. A list of multiple IP addresses through which the particular data protection appliance can be reached according to the stored information is returned to the client. The client, upon receipt of the list, selects an IP address from the list to attempt an initial connection to the particular data protection appliance.