Preserving configuration information in a SCAM based SCSI system

A method, comprising;

• in a first isolating step, isolating a first device coupled to a SCSI bus;
• transferring a first plurality of identification bits from said first device to a second device coupled to said SCSI bus;
• from said first plurality of identification bits, obtaining a second plurality of identification bits, there being fewer of said second plurality of identification bits than there are of said first plurality of identification bits;
• and
• storing said second plurality of identification bits in a non-volatile memory in said second device, wherein said first plurality of bits comprises a plurality of bits A and another plurality of bits B;
• wherein said second plurality of bits comprises a plurality of bits C and another plurality of bits D, and wherein said obtaining step comprises:
• using a first method to obtain from said plurality of bits A said plurality of bits C;
• and
• using a second method to obtain from said plurality of bits B said plurality of bits D.

A method, comprising:

• in a first SCAM isolating step, isolating a first device coupled to a SCSI bus;
• transferring a first plurality of identification bits from said first device to a second device coupled to said SCSI bus;
• using a first method, obtaining a second plurality of identification bits from said first plurality of identification bits, there being substantially fewer of said second plurality of identification bits than there are of said first plurality of identification bits;
• storing said second plurality of identification bits in a non-volatile memory in said second device;
• in a second SCAM isolating step, isolating a third device coupled to said SCSI bus;
• transferring a third plurality of identification bits from said third device to said second device;
• using said first method, obtaining a fourth plurality of identification bits from said third plurality of identification bits, there being substantially fewer of said fourth plurality of identification bits than there are of said third plurality of identification bits;
• and
• if said fourth plurality of identification bits is identical to said second plurality of identification bits, using a second method to obtain a fifth plurality of identification bits from said third plurality of bits, there being substantially fewer of said fifth plurality of identification bits than there are of said third plurality of identification bits.

Host adapter interface circuitry, comprising:

• means for receiving a first SCAM identification string from a SCSI bus, said first SCAM identification string comprising a first plurality of bits A and a second plurality of bits B;
• means for obtaining a third plurality of bits C from said first plurality of bits A using a first method and for obtaining a fourth plurality of bits D from said second plurality of bits B using a second method;
• and
• a non-volatile memory storing said third plurality of bits C and said fourth plurality of bits D.

Host adapter interface circuitry, comprising:

• means for receiving a first SCAM identification string from a SCSI bus, said first SCAM identification string comprising a first plurality of bits A and a second plurality of bits B;
• means for obtaining a third plurality of bits C from said first plurality of bits A using a first method and for obtaining a fourth plurality of bits D from said second plurality of bits B using a second method;
• and
• a non-volatile memory storing said third plurality of bits C and said fourth plurality of bits D;
• wherein said means for receiving also receives a second SCAM identification string, said second SCAM identification string comprising a first plurality of bits A and a second plurality of bits B, and wherein said means for obtaining is also for:
• using a third method to obtain a fifth plurality of bits E from said first plurality of bits A of said second SCAM identification string if said third plurality of bits C obtained from said first plurality of bits A of said first SCAM identification string using said first method is identical to a third plurality of bits C obtained from said first plurality of bits A of said second SCAM identification string using said first method, said fifth plurality of bits E being different than said third plurality of bits C obtained from said first plurality of bits A of said first SCAM identification string using said first method.

Host adapter circuitry, comprising:

• a non-volatile memory;
• means for hashing a first SCSI identification string from a first peripheral coupled to a SCSI bus down into a first smaller string of bits and for storing the first smaller string of bits in said non-volatile memory, and for hashing a second SCSI identification string from a second peripheral coupled to said SCSI bus down into a second smaller string of bits and for storing the second smaller string of bits in said non-volatile memory;
• and
• means for preventing a logical system identifier associated with said first peripheral from being changed if said second peripheral is decoupled from said SCSI bus, and for preventing a logical system identifier associated with said second peripheral from being changed if said first peripheral is decoupled from said SCSI bus.