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Cisco Bug: CSCul08797 - FICON tape acceleration performance is slow

Last Modified

Mar 16, 2016

Products (1)

  • Cisco MDS 9000 Series Multilayer Switches

Known Affected Releases

5.2(2)

Description (partial)

Symptom:
FICON attached Tape, Tape Library, or Virtual Tape Library may experience mounts not being honored when Cisco MDS Fiber Channel/FICON switch is configured for FICON Tape Acceleration (FTA) over FCIP interface. Under some conditions, the Host/Mainframe may send a Write (0x1) command before a tape has been properly made ready by the Library (seen in robot assisted library). The Control Unit  (i.e. library) returns a status for the Write command with either:
a) Channel End (CE), Device End (DE), with Unit Check (UC) 
b) Splits the status by sending a single CE, followed by the DE/UC. 

In the case of the split status (b), FTA enters Write Acceleration early. Once CU has properly mounted the tape  an asynchronous status of Unit Attention (UA) is sent to inform Host that tape is ready. This UA status is dropped in error causing the tape to not mount.

Conditions:
Symtom is observed when Cisco MDS switch is configured for FICON Tape Acceleration and Tape Library with Mechanical Robot is being extended.
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