Guaranteed delivery in receiver side overcommitted communication adapters

A system comprising:

• a memory having computer readable instructions;
• and
• one or more processors for executing the computer readable instructions, the computer readable instructions controlling the one or more processors to perform operations comprising:
• receiving an input/output (I/O) request comprising a data stream from a host processor, the I/O request further comprising look ahead information and a look ahead type field for specifying a type of the look ahead information, the type one of quality of service and anticipated buffer count, the receiving at a network adapter of a storage controller that manages storage for the host processor, the storage controller comprising a storage buffer to store data received from the host processor before migrating it to the storage, and the storage controller further comprising a data cache and a control unit;
• assigning, by the control unit, a sequence tag to the data stream, the sequence tag indicating an order of receiving the data stream at the network adapter;
• determining whether the storage buffer has enough free space to store the received data stream;
• storing, by the control unit, the received data stream in the storage buffer based at least in part on determining that the storage buffer has enough free space to store the received data stream;
• storing, by the control unit, the received data stream in the data cache based at least in part on determining that the storage buffer does not have enough free space to store the received data stream;
• and
• based at least in part on storing the received data stream in the data cache:
• determining an amount of free space in the storage buffer;
• and
• moving the received data stream from the data cache to the storage buffer based on the amount of free space in the storage buffer being greater than an estimated amount of space required to store the received data stream and the sequence tag indicating that the data stream was received prior to any other data stream currently stored in the data cache.

A computer program product comprising a non-transitory computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor to cause the processor to perform operations comprising:

• receiving an input/output (I/O) request comprising a data stream from a host processor, the I/O request further comprising look ahead information and a look ahead type field for specifying a type of the look ahead information, the type one of quality of service and anticipated buffer count, the receiving at a network adapter of a storage controller that manages storage for the host processor, the storage controller comprising a storage buffer to store data received from the host processor before migrating it to the storage, and the storage controller further comprising a data cache and a control unit/O operation on the logical data path;
• assigning, by the control unit, a sequence tag to the data stream, the sequence tag indicating an order of receiving the data stream at the network adapter;
• determining whether the storage buffer has enough free space to store the received data stream;
• storing, by the control unit, the received data stream in the storage buffer based at least in part on determining that the storage buffer has enough free space to store the received data stream;
• storing, by the control unit, the received data stream in the data cache based at least in part on determining that the storage buffer does not have enough free space to store the received data stream;
• and
• based at least in part on storing the received data stream in the data cache:
• determining an amount of free space in the storage buffer;
• and
• moving the received data stream from the data cache to the storage buffer based on the amount of free space in the storage buffer being greater than an estimated amount of space required to store the received data stream and the sequence tag indicating that the data stream was received prior to any other data stream currently stored in the data cache.