Ubuntu Manpage: sg_read_long - send a SCSI READ LONG command

Provided by: sg3-utils_1.36-1ubuntu1_amd64

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.

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
informative 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
default) does not match the "long" block size of the device, the appropriate BTL is
deduced 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
       hexadecimal. 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 © 2004-2010 Douglas Gilbert
       This software is distributed under the GPL version 2. There is NO warranty; not  even  for
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.