sg_read_long - send the scsi command read long

sg_read_long [--correct] [--help] [--lba=<num>] [--out=<name>] [--verbose] [--version] [--xfer_len=<num>] <scsi_device>

Send READ LONG command to a Linux SCSI 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.

--correct | -c sets the 'CORRCT' bit in the READ LONG SCSI 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.

--help | -h

output the usage message then exit.

--lba=<num> | -l <num>

the logical block address of the sector to read. Assumed to be in decimal unless prefixed with '0x'. Defaults to lba 0. Only 32 bit lbas currently supported.

--out=<name> | -o <name>

instead of outputting ASCII hex to stdout, try to send it to the file called <name>. If '-' is given as the <name> then the (binary) output is sent to stdout. Note that all informative and error output is sent to stderr.

--verbose | -v

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

--version | -V

print the version string and then exit.

--xfer_len=<num> | -x <num>

the transfer length in bytes (default to 520). If the given value (or the default) does not match the "long" block size of the device, the appropriate xfer_len value is derived from the error response and printed (to stderr). The idea is that the user will retry this utility with the correct transfer length.

The lba and xfer_len numerical arguments may be followed by the following multiplicative suffixes: c C *1; w W *2; b B *512; k K KiB *1,024; KB *1,000; m M MiB *1,048,576; MB *1,000,000; g G GiB *1,073,741,824; and GB *1,000,000,000 . Also a suffix of the form "x<n>" multiplies the leading number by <n>.

Alternatively numerical values can be given in hexadecimal preceded by either "0x" or "0X". When hex numbers are given multipliers cannot be used.

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.]

Written by Douglas Gilbert.

Report bugs to <dgilbert at interlog dot com>.

Copyright © 2004-2005 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.

sg_write_long, sg_dd