Provided by: sg3-utils_1.42-2ubuntu1.18.04.2_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. 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 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 © 2004-2016 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.
SEE ALSO
sg_reassign, sg_write_long, sg_dd