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SG_READ_LONG(8)                               SG3_UTILS                              SG_READ_LONG(8)



NAME
       sg_read_long - send a SCSI READ LONG command

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

DESCRIPTION
       Send SCSI READ LONG command to DEVICE. The read buffer is output in hex and ASCII  to  stdout
       or  placed  in a file. Note that the data returned includes the logical block data (typically
       512 bytes for a disk) plus ECC information (whose  format  is  proprietary)  plus  optionally
       other proprietary data. Note that the logical block data may be encoded or encrypted.

       In  SBC-4  revision 7 the SCSI READ LONG (10 and 16 byte) commands were made obsolete. In the
       same revision all uses of SCSI WRITE LONG (10 and 16 byte) commands were made obsolete  apart
       from the case in which the WR_UNCOR bit is set.

OPTIONS
       Arguments to long options are mandatory for short options as well.

       -S, --16
              uses  a  SCSI READ LONG(16) command. The default action is to use a SCSI READ LONG(10)
              command. The READ LONG(10) command has a 32 bit field for the lba while READ  LONG(16)
              has a 64 bit field.

       -c, --correct
              sets the 'CORRCT' bit in the SCSI READ LONG command. When set the data is corrected by
              the ECC before being transferred back to this utility. The default  is  to  leave  the
              'CORRCT' bit clear in which case the data is not corrected.

       -h, --help
              output the usage message then exit.

       -l, --lba=LBA
              where LBA is the logical block address of the sector to read. Assumed to be in decimal
              unless prefixed with '0x' (or has a trailing 'h'). Defaults to lba 0. If  the  lba  is
              larger than can fit in 32 bits then the --16 option should be used.

       -o, --out=OF
              instead of outputting ASCII hex to stdout, send it in binary to the file called OF. If
              '-' is given for OF then the (binary) output is sent to stdout. Note that all informa‐
              tive and error output is sent to stderr.

       -p, --pblock
              sets the 'PBLOCK' bit in the SCSI READ LONG command. When set the physical block (plus
              ECC data) containing the requested logical block address is read. The  default  is  to
              leave  the  'PBLOCK'  bit clear in which case the logical block (plus any ECC data) is
              read.

       -r, --readonly
              opens the DEVICE read-only rather than read-write which is the default. The  Linux  sg
              driver needs read-write access for the SCSI READ LONG command but other access methods
              may require read-only access.

       -v, --verbose
              increase the level of verbosity, (i.e. debug output).

       -V, --version
              print the version string and then exit.

       -x, --xfer_len=BTL
              where BTL is the byte transfer length (default to 520). If the given value (or the de‐
              fault)  does not match the "long" block size of the device, the appropriate BTL is de‐
              duced from the error response and printed (to stderr). The idea is that the user  will
              retry this utility with the correct transfer length.

NOTES
       If a defective block is found and its contents, if any, has been retrieved then "sg_reassign"
       could be used to map out the defective block. Associated with such an action  the  number  of
       elements  in  the  "grown" defect list could be monitored (with "sg_reassign --grown") as the
       disk could be nearing the end of its useful lifetime.

       Various numeric arguments (e.g. LBA) may include multiplicative suffixes or be given in hexa‐
       decimal. See the "NUMERIC ARGUMENTS" section in the sg3_utils(8) man page.

       As  a data point, Fujitsu uses a 54 byte ECC (per block) which is capable of correcting up to
       a single burst error or 216 bits "on the fly". [Information obtained from  MAV20xxrc  product
       manual.]

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

AUTHORS
       Written by Douglas Gilbert.

REPORTING BUGS
       Report bugs to <dgilbert at interlog dot com>.

COPYRIGHT
       Copyright © 2004-2016 Douglas Gilbert
       This software is distributed under the GPL version 2. There is NO warranty; not even for MER‐
       CHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

SEE ALSO
       sg_reassign, sg_write_long, sg_dd



sg3_utils-1.42                              November 2015                            SG_READ_LONG(8)