sg_write_long.8

.TH SG_WRITE_LONG "8" "January 2007" "sg3_utils\-1.23" SG3_UTILS
.SH NAME
sg_write_long \- send the SCSI WRITE LONG command
.SH SYNOPSIS
.B sg_write_long
[\fI\-\-16\fR] [\fI\-\-cor_dis\fR] [\fI\-\-help\fR] [\fI\-\-in=IF\fR]
[\fI\-\-lba=LBA\fR] [\fI\-\-pblock\fR] [\fI\-\-verbose\fR]
[\fI\-\-version\fR] [\fI\-\-wr_uncor\fR] [\fI\-\-xfer_len=BTL\fR]
\fIDEVICE\fR
.SH DESCRIPTION
.\" Add any additional description here
.PP
Send the SCSI WRITE LONG (10 or 16 byte) command to \fIDEVICE\fR. The buffer
to be written to the \fIDEVICE\fR is filled with
.B 0xff
bytes or read from the \fIIF\fR file. This buffer includes the logical
data (e.g. 512 bytes) and the ECC bytes.
.PP
This utility can be used to generate a MEDIUM ERROR at a specific logical
block address. This can be useful for testing error handling. Prior to
such a test, the
.B sg_dd
utility could be used to copy the original contents of the logical
block address to some safe location. After the test the
.B sg_dd
utility could be used to write back the original contents of the
logical block address. An alternate strategy would be to read the "long"
contents of the logical block address with
.B sg_read_long
utility prior to testing and restore it with this utility after testing.
.PP
.B Take care:
If recoverable errors are being injected (e.g. only one or a few bits
changed so that the ECC is able to correct the data) then care should
be taken with the settings in the "read write error recovery" mode page.
Specifically if the ARRE (for reads) and/or AWRE (for writes) are set
then recovered errors will cause the lba to be reassigned (and the old
location to be added to the grown defect list (PLIST)). This is not easily 
reversed and uses the (finite number) of spare sectors set aside for
this purpose. If in doubt it is probably safest to clear the ARRE and
AWRE bits. These bits can be checked and modified with the sdparm utility.
For example: "sdparm \-c AWRE,ARRE /dev/sda" will clear the bits until
the disk is rebooted.
.SH OPTIONS
Arguments to long options are mandatory for short options as well.
.TP
\fB\-S\fR, \fB\-\-16\fR
send a SCSI WRITE LONG (16) command to \fIDEVICE\fR. The default action (in
the absence of this option) is to send a SCSI WRITE LONG (10) command.
.TP
\fB\-c\fR, \fB\-\-cor_dis\fR
sets the correction disabled (i.e 'COR_DIS') bit. This inhibits various
other mechanisms such as automatic block reallocation, error recovery
and various informational exception conditions being triggered.
This bit is new in SBC\-3 .
.TP
\fB\-h\fR, \fB\-\-help\fR
output the usage message then exit.
.TP
\fB\-i\fR, \fB\-\-in\fR=\fIIF\fR
read data (binary) from file named \fIIF\fR and use it for the SCSI WRITE
LONG command. If \fIIF\fR is "\-" then stdin is read. If this option is
not given then 0xff bytes are used as fill.
.TP
\fB\-l\fR, \fB\-\-lba\fR=\fILBA\fR
where \fILBA\fR is the logical block address of the sector to overwrite.
Defaults to lba 0 which is a dangerous block to overwrite on a disk that is
in use. Assumed to be in decimal unless prefixed with '0x' or has a
traling 'h'. If \fILBA\fR is larger than can fit in 32 bits then the
\fI\-\-16\fR option should be used.
.TP
\fB\-p\fR, \fB\-\-pblock\fR
sets the physical block (i.e 'PBLOCK') bit. This instructs \fIDEVICE\fR
to use the given data (unless \fI\-\-wr_uncor\fR is also given) to write
to the physical block specified by \fILBA\fR. The default action
is to write to the logical block corresponding to the given lba.
This bit is new in SBC\-3 .
.TP
\fB\-v\fR, \fB\-\-verbose\fR
increase the degree of verbosity (debug messages).
.TP
\fB\-V\fR, \fB\-\-version\fR
output version string then exit.
.TP
\fB\-w\fR, \fB\-\-wr_uncor\fR
sets the "write uncorrected" (i.e 'WR_UNCOR') bit. This instructs the
\fIDEVICE\fR to flag the given lba (or the physical block that contains it
if \fI\-\-pblock\fR is also given) as having an unrecoverable error
associated with it. Note: no data is transferred to \fIDEVICE\fR,
other than the command (i.e. the cdb). The default action is to
use the provided data (\fI\-\-xfer_len=BTL\fR in length) and write it to
\fIDEVICE\fR.  This bit is new in SBC\-3 .
.TP
\fB\-x\fR, \fB\-\-xfer_len\fR=\fIBTL\fR
where \fIBTL\fR 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, nothing is written to \fIDEVICE\fR and the appropriate xfer_len value
may be deduced from the error response which is printed (to stderr).
.SH NOTES
The \fILBA\fR and \fIBTL\fR (transfer length) 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>.
.PP
Alternatively numerical values can be given in hexadecimal preceded by
either "0x" or "0X" (or with a trailing "h" or "H"). When hex numbers are
given, multipliers cannot be used.
.PP
To read from a defective sector (that, for example, has been filled with
0xff bytes by this utility) use:
.PP
  sg_dd if=\fIDEVICE\fR skip=\fILBA\fR of=/dev/null bs=512 count=1
.PP
To overwrite to a defective sector use:
.PP
  sg_dd of=\fIDEVICE\fR seek=\fILBA\fR if=/dev/zero bs=512 count=1    
.PP
This will result in a sector (block) with 512 bytes of 0x0 without a
MEDIUM ERROR since the ECC and associated data will be well formed.
.PP
The 10 byte SCSI WRITE LONG command limits the logical block address
to a 32 bit quantity. For larger lbas use the \fI\-\-16\fR option for the
SCSI WRITE LONG (16) command.
.SH EXIT STATUS
The exit status of sg_write_long is 0 when it is successful. Otherwise see
the sg3_utils(8) man page.
.SH AUTHORS
Written by Saeed Bishara. Further work by Douglas Gilbert.
.SH "REPORTING BUGS"
Report bugs to <dgilbert at interlog dot com>.
.SH COPYRIGHT
Copyright \(co 2004\-2007 Douglas Gilbert
.br
This software is distributed under the GPL version 2. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
.SH "SEE ALSO"
.B sg_read_long, sg_dd (both in sg3_utils), sdparm(sdparm)