sg_read_long(8)

1SG_READ_LONG(8)                    SG3_UTILS                   SG_READ_LONG(8)
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NAME

6       sg_read_long - send a SCSI READ LONG command
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SYNOPSIS

9       sg_read_long   [--16]   [--correct]   [--help]  [--lba=LBA]  [--out=OF]
10       [--pblock] [--readonly] [--verbose] [--version] [--xfer_len=BTL] DEVICE
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DESCRIPTION

13       Send SCSI READ LONG command to DEVICE. The read buffer is output in hex
14       and  ASCII  to  stdout or placed in a file. Note that the data returned
15       includes the logical block data (typically 512 bytes for a  disk)  plus
16       ECC  information  (whose  format  is proprietary) plus optionally other
17       proprietary data. Note that the logical block data may  be  encoded  or
18       encrypted.
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20       In  SBC-4  revision 7 the SCSI READ LONG (10 and 16 byte) commands were
21       made obsolete. In the same revision all uses of SCSI WRITE LONG (10 and
22       16  byte)  commands were made obsolete apart from the case in which the
23       WR_UNCOR bit is set.
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OPTIONS

26       Arguments to long options are mandatory for short options as well.
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28       -S, --16
29              uses a SCSI READ LONG(16) command. The default action is to  use
30              a SCSI READ LONG(10) command. The READ LONG(10) command has a 32
31              bit field for the lba while READ LONG(16) has a 64 bit field.
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33       -c, --correct
34              sets the 'CORRCT' bit in the SCSI READ LONG  command.  When  set
35              the  data  is corrected by the ECC before being transferred back
36              to this utility. The default is to leave the 'CORRCT' bit  clear
37              in which case the data is not corrected.
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39       -h, --help
40              output the usage message then exit.
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42       -l, --lba=LBA
43              where  LBA  is  the logical block address of the sector to read.
44              Assumed to be in decimal unless prefixed with  '0x'  (or  has  a
45              trailing  'h'). Defaults to lba 0. If the lba is larger than can
46              fit in 32 bits then the --16 option should be used.
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48       -o, --out=OF
49              instead of outputting ASCII hex to stdout, send it in binary  to
50              the  file  called  OF.  If '-' is given for OF then the (binary)
51              output is sent to stdout. Note that all  informative  and  error
52              output is sent to stderr.
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54       -p, --pblock
55              sets  the  'PBLOCK'  bit in the SCSI READ LONG command. When set
56              the physical block (plus ECC data) containing the requested log‐
57              ical block address is read. The default is to leave the 'PBLOCK'
58              bit clear in which case the logical block (plus any ECC data) is
59              read.
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61       -r, --readonly
62              opens  the  DEVICE read-only rather than read-write which is the
63              default. The Linux sg driver needs  read-write  access  for  the
64              SCSI  READ  LONG  command  but  other access methods may require
65              read-only access.
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67       -v, --verbose
68              increase the level of verbosity, (i.e. debug output).
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70       -V, --version
71              print the version string and then exit.
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73       -x, --xfer_len=BTL
74              where BTL is the byte transfer length (default to 520).  If  the
75              given  value  (or  the  default) does not match the "long" block
76              size of the device, the appropriate  BTL  is  deduced  from  the
77              error  response  and  printed  (to stderr). The idea is that the
78              user will retry this utility with the correct transfer length.
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NOTES

81       If a defective block is found  and  its  contents,  if  any,  has  been
82       retrieved  then  "sg_reassign"  could  be used to map out the defective
83       block. Associated with such an action the number  of  elements  in  the
84       "grown"  defect list could be monitored (with "sg_reassign --grown") as
85       the disk could be nearing the end of its useful lifetime.
86
87       Various numeric arguments (e.g. LBA) may  include  multiplicative  suf‐
88       fixes  or  be given in hexadecimal. See the "NUMERIC ARGUMENTS" section
89       in the sg3_utils(8) man page.
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91       As a data point, Fujitsu uses a 54 byte ECC (per block) which is  capa‐
92       ble  of correcting up to a single burst error or 216 bits "on the fly".
93       [Information obtained from MAV20xxrc product manual.]
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EXIT STATUS

96       The exit status of sg_read_long is 0 when it is  successful.  Otherwise
97       see the sg3_utils(8) man page.
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AUTHORS

100       Written by Douglas Gilbert.
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REPORTING BUGS

103       Report bugs to <dgilbert at interlog dot com>.
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COPYRIGHT

106       Copyright © 2004-2016 Douglas Gilbert
107       This  software is distributed under the GPL version 2. There is NO war‐
108       ranty; not even for MERCHANTABILITY or FITNESS FOR  A  PARTICULAR  PUR‐
109       POSE.
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