Patent ID: 8140763

Claim:
A method for limiting an amount of write data stored in a cache memory of a storage controller, the method comprising: determining a usable region of a non-volatile storage (NVS) of the storage controller; determining an amount of write data in a current write request for the cache memory; determining a failure boundary associated with the current write request; maintaining a count of write data associated with the failure boundary; and rejecting the current write request for the cache memory when a sum of the count of the write data associated with the failure boundary and the write data in the current write request exceeds a determined percentage of the usable region of the NVS, wherein the failure boundary is for a set of ranks that are associated with a fabric attaching devices to the storage controller such that a failure of the fabric causes loss of access to the set of ranks and the count associated with the failure boundary corresponds to a sum of the write data for the associated ranks in the failure boundary that were issued to volumes that can map a write request directly to a single rank at the time the write is issued.