Hi,
Thanks for everyone who repsonds so far:
Those repsonds suggest me to use the "-o full" flags to get a more
detail report which I did:
********************  extract from  entry 1 ************************ 
----- UNIT INFORMATION -----
CLASS                         x0001     TAPE 
SUBSYSTEM                     x0000     DISK 
BUS #                         x0000
ERROR TYPE                              Hard Error Detected 
----- CAM STRING -----
DEVICE NAME                             UNKNOWN 
----- CAM STRING -----
                                        Active CCB at time of error 
Comment:
The first and second attempt for backup fails, but the third one succeeds.
So what happen?  May be the termination is not proper or SCSI too long?
Any suggestion?
********************  extract from  entry 2 ************************ 
----- UNIT INFORMATION -----
CLASS                         x0022     DEC SIM 
SUBSYSTEM                     x0000     DISK 
BUS #                         x0001
                              x0070     LUN x0
                                        TARGET x6
----- CAM STRING -----
ROUTINE NAME                            sm_unexpected 
----- CAM STRING -----
                                        Unexpected bus free 
I have no ideas at all for this error, how about you?
--Sunny Siu
  Unix system admin., ACS
  University of Texas at Arlington
  siu_at_uta.edu
> uname -a
> OSF1 omega V2.1 250 alpha
The following is the complete listing of the error reported by uerf.
                                                  uerf version 4.2-011 (120)
********************************* ENTRY     1. *********************************
----- EVENT INFORMATION -----
EVENT CLASS                             ERROR EVENT 
OS EVENT TYPE                  199.     CAM SCSI 
SEQUENCE NUMBER                 46.
OPERATING SYSTEM                        DEC OSF/1 
OCCURRED/LOGGED ON                      Wed Nov  8 08:19:29 1995
OCCURRED ON SYSTEM                      omega 
SYSTEM ID                 x0004000F     CPU TYPE: DEC 
                                        CPU SUBTYPE: KN15AA 
----- UNIT INFORMATION -----
CLASS                         x0001     TAPE 
SUBSYSTEM                     x0000     DISK 
BUS #                         x0000
                              x0008     LUN x0
                                        TARGET x1
----- CAM STRING -----
ROUTINE NAME                            ctape_wfm 
----- CAM STRING -----
ERROR TYPE                              Hard Error Detected 
----- CAM STRING -----
DEVICE NAME                             UNKNOWN 
----- CAM STRING -----
                                        Active CCB at time of error 
----- CAM STRING -----
                                        CCB request completed with an error 
ERROR - os_std, os_type = 11, std_type = 10
----- ENT_CCB_SCSIIO -----
*MY ADDR                  x9005D728
CCB LENGTH                    x00C0
FUNC CODE            x01
CAM_STATUS                    x0084     CAM_REQ_CMP_ERR 
                                        AUTOSNS_VALID 
PATH ID              0.
TARGET ID            1.
TARGET LUN           0.
CAM FLAGS                 x000000C0
                                        CAM_DIR_NONE 
*PDRV_PTR                 x9005D428
*NEXT_CCB                 x00000000
*REQ_MAP                  x00000000
VOID (*CAM_CBFCNP)()      x0040DC10
*DATA_PTR                 x00000000
DXFER_LEN                 x00000000
*SENSE_PTR                x9005D450
SENSE_LEN            x40
CDB_LEN              x06
SGLIST_CNT                    x0000
CAM_SCSI_STATUS               x0002     SCSI_STAT_CHECK_CONDITION 
SENSE_RESID          x26
RESID                     x00000000
CAM_CDB_IO           x000000000000000100000010
CAM_TIMEOUT               x0000012D
MSGB_LEN                      x0000
VU_FLAGS                      x0000
TAG_ACTION           x00
----- CAM STRING -----
                                        Error, exception, or abnormal 
                                         _condition 
----- CAM STRING -----
                                        MEDIUM ERROR - Nonrecoverable medium 
                                         _error 
----- ENT_SENSE_DATA -----
ERROR CODE                    x0070     CODE x70
SEGMENT              x00
SENSE KEY                     x0003     MEDIUM ERR 
INFO BYTE 3          x00
INFO BYTE 2          x00
INFO BYTE 1          x00
INFO BYTE 0          x01
ADDITION LEN         x12
CMD SPECIFIC 3       x00
CMD SPECIFIC 2       x00
CMD SPECIFIC 1       x00
CMD SPECIFIC 0       x00
ASC                  x0C
ASQ                  x00
FRU                  x00
SENSE SPECIFIC       x000000
ADDITIONAL SENSE    
0000:   00000000  13C01D00  00000313  00000000        *................*
0010:   00000000  00000000  00000000  00000000        *................*
0020:   00000000  00000000  00000000  00000000        *................*
0030:   7E250000  00005E3C  00000000  00000000        *..%~<^..........*
********************************* ENTRY     2. *********************************
----- EVENT INFORMATION -----
EVENT CLASS                             ERROR EVENT 
OS EVENT TYPE                  199.     CAM SCSI 
SEQUENCE NUMBER                 44.
OPERATING SYSTEM                        DEC OSF/1 
OCCURRED/LOGGED ON                      Tue Nov  7 15:07:29 1995
OCCURRED ON SYSTEM                      omega 
SYSTEM ID                 x0004000F     CPU TYPE: DEC 
                                        CPU SUBTYPE: KN15AA 
----- UNIT INFORMATION -----
CLASS                         x0022     DEC SIM 
SUBSYSTEM                     x0000     DISK 
BUS #                         x0001
                              x0070     LUN x0
                                        TARGET x6
----- CAM STRING -----
ROUTINE NAME                            sm_unexpected 
----- CAM STRING -----
                                        Unexpected bus free 
----- UNSUPPORTED ENTRY -----
CAM ENTRY                 x0000040E     SIM_WS 
Received on Wed Nov 08 1995 - 22:43:57 NZDT