[Sunhelp] Help reqd for SCSI errors !!

[Shivraj Yadav CS -hyd]

Hi Friends!
I am having a SPARC SERVER 1000 with 2 internal HDD & around 4 external
HDD, one of 'em being kept in a shoe-box.
Nowadays while booting also otherwise when the system is functioning, i
keep on getting the following messgaes on the console.....

WARNING: /io-unit at f,e1200000/sbi at 0,0/dma at 0,81000/esp at 0,800000 (esp2):
1)UNIX:Target 3.0 reducing sync transfer rate
"SCSI transport failed : reason 'time out': retrying command
2) "SCSI transport failed : reason 'reset':retrying command
3) "Connected command timeout for target 3.0 "

I need help in finding out where the problem is. Is it is the HDD or the
cable connecting to it ?????
What's the difference in the above three messages.
Thanks in advance .....
SHIVRAJ