Provided by: sg3-utils_1.46-3ubuntu4_amd64 
NAME
sg_xcopy - copy data to and from files and devices using SCSI EXTENDED COPY (XCOPY)
SYNOPSIS
sg_xcopy [bs=BS] [conv=CONV] [count=COUNT] [ibs=BS] [if=IFILE] [iflag=FLAGS] [obs=BS] [of=OFILE]
[oflag=FLAGS] [seek=SEEK] [skip=SKIP] [--help] [--version]
[app=0|1] [bpt=BPT] [cat=0|1] [dc=0|1] [fco=0|1] [id_usage={hold|discard|disable}] [list_id=ID]
[prio=PRIO] [time=0|1] [verbose=VERB] [--on_dst|--on_src] [--verbose]
DESCRIPTION
Copy data to and from any files. Specialized for "files" that are Linux SCSI devices that support the
SCSI EXTENDED COPY (XCOPY) command.
This utility has similar syntax and semantics to dd(1) but with no "conversions" is supported.
The first group in the synopsis above are "standard" Unix dd(1) operands. The second group are extra
options added by this utility. Both groups are defined below in combined, alphabetical order.
By default the XCOPY command is sent to OFILE. This can be changed with the --on_src or iflag=xflag
options which cause the XCOPY command to be sent to IFILE instead. Also see the section on ENVIRONMENT
VARIABLES.
In the SPC-4 standard the T10 committee has expanded the XCOPY command so that it now has two variants:
"LID1" (for a List Identifier length of 1 byte) and "LID4" (for a List Identifier length of 4 bytes).
This utility supports the older, LID1 variant which is also found in SPC-3 and earlier. While the LID1
variant in SPC-4 is command level (binary) compatible with XCOPY as defined in SPC-3, some of the command
naming has changed. This utility uses the older, SPC-3 XCOPY names.
The ddpt utility supports the same xcopy(LID1) functionality as this utility with the same options and
flags. Additionally ddpt supports a subset of xcopy(LID4) functionality variously called "xcopy version
2, lite" or ODX. ODX is a market name and stands for Offloaded Data Xfer (i.e. transfer).
OPTIONS
app={0|1}
if 1 start the destination of the copy at the end of OFILE. This assumes that OFILE is a regular
file. The default is 0 in which case the destination of the copy starts at the beginning of OFILE
(possibly offset be SEEK). This option cannot be used with the seek=SEEK option.
bpt=BPT
each IO transaction will be made using BPT blocks (or less if near the end of the copy). Default
is 128 for logical block sizes less that 2048 bytes, otherwise the default is 32. So for bs=512
the reads and writes will each convey 64 KiB of data by default (less if near the end of the
transfer or memory restrictions). When cd/dvd drives are accessed, the logical block size is
typically 2048 bytes and bpt defaults to 32 which again implies 64 KiB transfers.
bs=BS where BS must be the logical block size of the physical device (if either the input or output
files are accessed via SCSI commands). Note that this differs from dd(1) which permits BS to be an
integral multiple. Defaults to the device logical block size.
cat={0|1}
sets the SCSI EXTENDED COPY command segment descriptor CAT bit to 0 or 1 (default: 0). The CAT bit
(in conjunction with the PAD bit) controls the handling of residual data. See section HANDLING OF
RESIDUAL DATA for details.
conv=CONV
all CONV arguments are ignored.
count=COUNT
copy COUNT blocks from IFILE to OFILE. Default is the minimum (IFILE if dc=0 or OFILE if dc=1)
number of blocks that SCSI devices report from SCSI READ CAPACITY commands or that block devices
(or their partitions) report. Normal files are not probed for their size. If skip=SKIP or
seek=SEEK are given and the count is derived (i.e. not explicitly given) then the derived count is
scaled back so that the copy will not overrun the device. If the file name is a block device
partition and COUNT is not given then the size of the partition rather than the size of the whole
device is used. If COUNT is not given (or count=-1) and cannot be derived then an error message is
issued and no copy takes place.
dc={0|1}
sets the SCSI EXTENDED COPY command segment descriptor DC bit to 0 or 1 (default: 0). The DC bit
controls whether COUNT refers to the source (dc=0) or the target (dc=1) descriptor.
fco={0|1}
sets the SCSI EXTENDED COPY command segment descriptor FCO bit to 0 or 1 (default: 0). The Fast
Copy Only (FCO) bit set will result in the copy being done but a technique faster than SCSI READ
and WRITE commands. If the copy cannot but done in a faster manner then a sense key of "Copy
aborted" with and additional sense of "Fast copy not possible" is returned.
ibs=BS if given must be the same as BS given to 'bs=' option.
id_usage={hold|discard|disable}
sets the SCSI EXTENDED COPY command parameter list field called LIST ID USAGE to 0 if the argument
is 'hold', to 2 if the argument is 'discard', or to '3' if the argument is 'disable'.
If the device has the ability to hold data (as indicated by "held data limit" being greater than
zero) then id_usage defaults to 'hold' otherwise it defaults to 'discard'.
if=IFILE
read from IFILE instead of stdin. If IFILE is '-' then stdin is read. Starts reading at the
beginning of IFILE unless SKIP is given.
iflag=FLAGS
where FLAGS is a comma separated list of one or more flags outlined below. These flags are
associated with IFILE and are ignored when IFILE is stdin.
list_id=ID
sets the SCSI EXTENDED COPY command parameter list field called LIST IDENTIFIER to ID. ID should
be a value between 0 and 255 (inclusive). ID usually defaults to 1 unless id_usage=disable in
which case it defaults to 0.
obs=BS if given must be the same as BS given to 'bs=' option.
of=OFILE
write to OFILE instead of stdout. If OFILE is '-' then writes to stdout. If OFILE is /dev/null
then no actual writes are performed. If OFILE is '.' (period) then it is treated the same way as
/dev/null (this is a shorthand notation). If OFILE exists then it is _not_ truncated; it is
overwritten from the start of OFILE unless 'oflag=append' or SEEK is given.
oflag=FLAGS
where FLAGS is a comma separated list of one or more flags outlined below. These flags are
associated with OFILE and are ignored when OFILE is /dev/null, '.' (period), or stdout.
prio=PRIO
sets the SCSI EXTENDED COPY command parameter list field called PRIORITY to PRIO. The default
value is 1.
seek=SEEK
start writing SEEK bs-sized blocks from the start of OFILE. Default is block 0 (i.e. start of
file).
skip=SKIP
start reading SKIP bs-sized blocks from the start of IFILE. Default is block 0 (i.e. start of
file).
time={0|1}
when 1, times transfer and does throughput calculation, outputting the results (to stderr) at
completion. When 0 (default) doesn't perform timing.
verbose=VERB
as VERB increases so does the amount of debug output sent to stderr. Default value is zero which
yields the minimum amount of debug output. A value of 1 reports extra information that is not
repetitive. A value 2 reports cdbs and responses for SCSI commands that are not repetitive (i.e.
other that READ and WRITE). Error processing is not considered repetitive. Values of 3 and 4 yield
output for all SCSI commands (and Unix read() and write() calls) so there can be a lot of output.
-h, --help
outputs usage message and exits.
--on_dst
send the XCOPY command to the output file/device (i.e. OFILE). This is the default unless
overridden by the --on_src or iflag=xflag options. Also see the section below on ENVIRONMENT
VARIABLES.
--on_src
send the XCOPY command to the input file/device (i.e. IFILE).
-v, --verbose
equivalent to verbose=1. When used twice, equivalent to verbose=2, etc.
-V, --version
outputs version number information and exits.
FLAGS
Here is a list of flags and their meanings:
append causes the O_APPEND flag to be added to the open of OFILE. For regular files this will lead to
data appended to the end of any existing data. Cannot be used together with the seek=SEEK option
as they conflict. The default action of this utility is to overwrite any existing data from the
beginning of the file or, if SEEK is given, starting at block SEEK. Note that attempting to
'append' to a device file (e.g. a disk) will usually be ignored or may cause an error to be
reported.
excl causes the O_EXCL flag to be added to the open of IFILE and/or OFILE.
flock after opening the associated file (i.e. IFILE and/or OFILE) an attempt is made to get an advisory
exclusive lock with the flock() system call. The flock arguments are "FLOCK_EX | FLOCK_NB" which
will cause the lock to be taken if available else a "temporarily unavailable" error is generated.
An exit status of 90 is produced in the latter case and no copy is done.
null has no affect, just a placeholder.
pad sets the SCSI EXTENDED COPY command segment descriptor PAD bit. The PAD bit (in conjunction with
the CAT bit) controls the handling of residual data.(See section HANDLING OF RESIDUAL DATA for
details.
xcopy has no affect; for compatibility with ddpt.
HANDLING OF RESIDUAL DATA
The pad and cat bits control the handling of residual data. As the data can be specified either in terms
of source or target logical block size and both might have different block sizes residual data is likely
to happen in these cases. If both logical block sizes are identical these bits have no effect as
residual data will not occur.
If none of these bits are set, the EXTENDED COPY command will be aborted with additional sense
'UNEXPECTED INEXACT SEGMENT'.
If only the cat bit is set the residual data will be retained and made available for subsequent segment
descriptors. Residual data will be discarded for the last segment descriptor.
If the pad bit is set for the source descriptor only, any residual data for both source or destination
will be discarded.
If the pad bit is set for the target descriptor only any residual source data will be handled as if the
cat bit is set, but any residual destination data will be padded to make a whole block transfer.
If the pad bit is set for both source and target any residual source data will be discarded, and any
residual destination data will be padded.
ENVIRONMENT VARIABLES
If the command line invocation does not explicitly (and unambiguously) indicate whether the XCOPY SCSI
command should be sent to IFILE (i.e. the source) or OFILE (i.e. the destination) then a check is made
for the presence of the XCOPY_TO_SRC and XCOPY_TO_DST environment variables. If either one exists (but
not both) then it indicates where the SCSI XCOPY command will be sent. By default the XCOPY command is
sent to OFILE.
RETIRED OPTIONS
Here are some retired options that are still present:
append=0 | 1
when set, equivalent to 'oflag=append'. When clear the action is to overwrite the existing file
(if it exists); this is the default. See the 'append' flag.
NOTES
Copying data behind an Operating System's back can cause problems. In the case of Linux, users should
look at this link: http://linux-mm.org/Drop_Caches
This command sequence may be useful:
sync; echo 3 > /proc/sys/vm/drop_caches
Various numeric arguments (e.g. SKIP) may include multiplicative suffixes or be given in hexadecimal. See
the "NUMERIC ARGUMENTS" section in the sg3_utils(8) man page.
The COUNT, SKIP and SEEK arguments can take 64 bit values (i.e. very big numbers). Other values are
limited to what can fit in a signed 32 bit number.
All informative, warning and error output is sent to stderr so that dd's output file can be stdout and
remain unpolluted. If no options are given, then the usage message is output and nothing else happens.
If a device supports xcopy operations then it should set the 3PC field (3PC stands for Third Party Copy)
in its standard INQUIRY response. This utility will attempt a xcopy operation irrespective of the value
in the 3PC field but if it is zero (cleared) one would expect the xcopy operation to fail.
The status of the SCSI EXTENDED COPY command can be queried with sg_copy_results(sg3_utils)
Currently only block-to-block transfers are implemented; IFILE and OFILE must refer to a SCSI block
device.
No account is taken of partitions so, for example, /dev/sbc2, /dev/sdc, /dev/sg2, and /dev/bsg/3:0:0:1
would all refer to the same thing: the whole logical unit (i.e. the whole disk) starting at LBA 0. So any
partition indication (e.g. /dev/sdc2) is ignored. The user should set SKIP, SEEK and COUNT with
information obtained from a command like 'fdisk -l -u /dev/sdc' to account for partitions.
XCOPY (LID1) capability has been added to the ddpt utility which is in a package of the same name. The
ddpt utility will run on other OSes (e.g. FreeBSD and Windows) while sg_xcopy only runs on Linux. Also
ddpt permits the arguments to ibs= and ibs= to be different.
EXAMPLES
Copy 2M of data from the start of one device to another:
# sg_xcopy if=/dev/sdo of=/dev/sdp count=2048 list_id=2 dc=1
sg_xcopy: if=/dev/sdo skip=0 of=/dev/sdp seek=0 count=1024
Start of loop, count=1024, bpt=65535, lba_in=0, lba_out=0
sg_xcopy: 1024 blocks, 1 command
Check the status of the EXTENDED COPY command:
# sg_copy_results --status --list_id=2 /dev/sdp
Receive copy results (copy status):
Held data discarded: Yes
Copy manager status: Operation completed without errors
Segments processed: 1
Transfer count units: 0
Transfer count: 0
SIGNALS
The signal handling has been borrowed from dd: SIGINT, SIGQUIT and SIGPIPE output the number of remaining
blocks to be transferred and the records in + out counts; then they have their default action. SIGUSR1
causes the same information to be output yet the copy continues. All output caused by signals is sent to
stderr.
EXIT STATUS
The exit status of sg_xcopy is 0 when it is successful. Otherwise see the sg3_utils(8) man page.
An additional exit status of 90 is generated if the flock flag is given and some other process holds the
advisory exclusive lock.
AUTHORS
Written by Hannes Reinecke and Douglas Gilbert.
REPORTING BUGS
Report bugs to <dgilbert at interlog dot com>.
COPYRIGHT
Copyright © 2000-2019 Hannes Reinecke and 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
There is a web page discussing sg_dd at http://sg.danny.cz/sg/sg_dd.html
A POSIX threads version of this utility called sgp_dd is in the sg3_utils package. Another version from
that package is called sgm_dd and it uses memory mapped IO to speed transfers from sg devices.
The lmbench package contains lmdd which is also interesting. For moving data to and from tapes see dt
which is found at http://www.scsifaq.org/RMiller_Tools/index.html
To change mode parameters that effect a SCSI device's caching and error recovery see sdparm(sdparm)
See also dd(1), sg_copy_results(sg3_utils), ddrescue(GNU), ddpt,ddptctl(ddpt)
sg3_utils-1.45 February 2019 SG_XCOPY(8)