ddptctl (8) - Linux Manuals
ddptctl: helper/auxiliary utility for ddpt
NAME
ddptctl - helper/auxiliary utility for ddptSYNOPSIS
ddptctl [--abort] [--all_toks] [--block] [--del_tkn] [--help] [--immed] [--info] [--list_id=LID] [--oir=OIR] [--poll] [--pt=GL] [--receive] [--rtf=RTF] [--rtype=RTYPE] [--size] [--timeout=ITO[,CMD]] [--verbose] [--version] [--wut=SL] [DEVICE]DESCRIPTION
This utility is a helper/auxiliary for the ddpt utility which copies data between or within SCSI devices (logical units). While ddpt's command line syntax is modelled on that of the POSIX dd command, this utility has a more standard Unix command line syntax with both short and long variants of each option.
The T10 committee defines a family of SCSI commands for offloaded copy. The central (but not the only) command is EXTENDED COPY often shortened to XCOPY or xcopy. There are now two generations of xcopy, the older one is given the suffix "LID1" and the newer one: "LID4". There is a subset of XCOPY(LID4) that supports disk to disk copies and is based on the SBC-3 commands: POPULATE TOKEN (PT) and WRITE USING TOKEN (WUT). ODX is a market name that has become associated with this subset. This utility can issue PT, WUT and related commands, read the Third Party Copy VPD page and perform several other housekeeping tasks.
The xcopy family of commands are described in the SPC-4 and SBC-3 documents found at http://www.t10.org .
OPTIONS
Arguments to long options are mandatory for short options as well.- -A, --abort
- this option will issue the COPY OPERATION ABORT command with the LID given in the --list_id=LID option. If the --list_id=LID option is not given then its default LID (257) is used. If there is an xcopy operation ongoing on this I-T nexus (i.e. issued by this machine to any LU sharing the same target) using that LID then the copy is aborted. Note there is a sense key (COPY ABORTED) indicating some but not all data has been copied due to this action.
- -a, --all_toks
- send the REPORT ALL ROD TOKENS SCSI command to DEVICE and decode the response. An ODX implementation is not required to support this command.
- -B, --block
- treat DEVICE as a block device when checking its --size. The default action of this utility is to treat DEVICE as a SCSI pass-through device.
- -D, --del_tkn
-
set the DEL_TKN bit in a WUT command (default: clear the DEL_TKN bit).
Since an ODX copy manager deletes the ROD Token after is has been
fully copied from (once), this option is typically not needed. It may
be useful for long-lived ROD Tokens that have only been partially
written from (or not used at all) and are no longer needed.
To delete an unused ROD Token a degenerate scatter list seems to be acceptable (e.g. '--wut=0,0 --del_tkn'). - -h, --help
- outputs the usage message summarizing command line options then exits.
- -I, --immed
- set the IMMED bit in the PT or WUT command. When given the PT and WUT commands return promptly before the data transfer is complete; then this utility exits. The user should then invoke the utility again with the --poll option and the same LID and DEVICE to await completion and receive the final transfer count. The default action of PT and WUT (i.e. without this option) is to wait for completion (i.e. all data transferred or an error occurs) before exiting this utility.
- -i, --info
-
when the DEVICE argument is given then check its Third Party Copy VPD
page and print out anything found. Also check if the 3PC bit is set in the
standard INQUIRY response.
If the DEVICE argument is not given and the --rtf=RTF option is given then decode part of the ROD Token held in the --RTF file. SPC-4 defines some parts of a ROD Token that can be decoded but does not require the copy manager to set these fields; so many fields may appear as zeros. A --RTF file that has been generated by the ddpt utility may contain multiple ROD Tokens, each optionally followed by an 8 byte "number of bytes represented" integer. They are all decoded, based on --RTF file length which should either be a multiple of 512 or 520 bytes. - -l, --list_id=LID
-
LID is a list identifier which is used to associate an originating
xcopy command (e.g. PT or WUT) with a follow-up command that retrieves
information or aborts the operation. T10 requires active LIDs to be
unique on a given I-T nexus. An I-T nexus is the current machine (more
precisely a HBA if a machine has two or more) and a specific target which
will contain one or more logical units (LUs) of which DEVICE is one.
If the DEVICE's copy manager feels that rather complex condition has
not been met then an error is generated with sense data that decodes
to "operation in progress". Rather than try to work out who is doing
what elsewhere, try another LID value.
The default value for LID is 257. - -O, --oir=OIR
- OIR is the Offset In ROD, a field in the WUT command. It may be be used together with the --wut=SL option. Its default value is 0 and its units are the logical block size of DEVICE.
- -p, --poll
-
send RECEIVE ROD TOKEN INFORMATION SCSI commands (RRTIs) to the DEVICE
using the LID (i.e. from the --list_id=LID option). If
a copy status is received indicating the operation is ongoing, then this
SCSI command is sent periodically (as suggested by the previous RRTI command
or 500 milliseconds) until some other copy status is detected. If the
--list_id=LID option is not given then a LID of 257 is assumed.
If the originating xcopy command was POPULATE TOKEN and the RRTI command indicates that it has completed successfully then the associated ROD Token (returned in the RRTI response) is written to the RTF file. If the --rtf=RTF option is not given then the ROD token is written to a file called ddptctl_rod_tok.bin in the current directory. - -P, --pt=GL
-
send a POPULATE TOKEN (PT) command with the given gather list. The format
of GL is given in the NOTES section. If used without the --immed
option then this utility, after the PT command finishes successfully, will
call the RRTI command. When the RRTI command finishes, potentially with a
new ROD Token, this utility will exit. Prior to that exit, if a new ROD
Token is available and the --rtf=RTF option is given then that
ROD Token is written to the RTF file. If the --rtf=RTF
option is not given then the ROD token is written to a file called
ddptctl_rod_tok.bin in the current directory.
If the --immed option is given this utility will exit after the PT command finishes. To complete the operation this utility should be invoked again with the --poll option and the same DEVICE. - -R, --receive
-
send the RECEIVE ROD TOKEN INFORMATION SCSI command (RRTI) to the DEVICE
using the LID (i.e. from the --list_id=LID option). If the
--list_id=LID option is not given then a LID of 257 is assumed.
If the originating xcopy command was POPULATE TOKEN and the RRTI command indicates that it has completed successfully then the associated ROD Token (returned in the RRTI response) is written to the RTF file. If the --rtf=RTF option is not given then the ROD token is written to a file called ddptctl_rod_tok.bin in the current directory. - -r, --rtf=RTF
-
when RTF is a file containing an ODX ROD Token or the name of a file
the ROD Token is to be written to. A ROD Token used by ODX is 512 bytes
long. If the RTF file was produced by the ddpt utility then it might
contain multiple ROD Tokens, each optionally followed by an 8 byte integer
containing the "number of bytes represented" by the preceding ROD Token.
If an RTF file with multiple ROD Tokens is given to this utility with --wut=SL then only the first ROD Token is used. If an RTF file is being decoded (i.e. no DEVICE argument given) then all ROD Tokens are decoded. - -t, --rtype=RTYPE
-
where RTYPE is the ROD Type, a field in the PT command (apart
from "zero"). The default value (0) indicates that the copy manager (in the
DEVICE) decides. RTYPE can be a decimal number, a hex
number (prefixed by 0x or with a "h" appended) or one
of "pit-def", "pit-vuln", "pit-pers", "pit-any" or "zero". The final
truncated word can be spelt out (e.g. "pit-vulnerable"). The "pit-"
lead-in stands for "point in time" copy.
The "zero" is a special case and is not given to a PT command. Instead it causes a special Block Device Zero Token to be created that can be used with the --wut=SL option to write blocks of zeros to the given DEVICE. - -s, --size
- prints the number of blocks and the size of each block for the given DEVICE. Protection information is printed if available. By default uses the pass-through interface and the READ CAPACITY command to obtain this information. If the --block option is given then the block layer in the OS is query for size information (and protection information is not reported).
- -T, --timeout=ITO[,CMD]
-
where ITO is the inactivity timeout (units: seconds) given to the
PT command. The default is 0 in which case the copy manager uses its own
default which is shown in the Third party Copy VPD page.
CMD is the SCSI command timeout (units: seconds) applied to SCSI commands issued by this utility; default is 0 which is translated to 600 seconds for originating xcopy commands (e.g. PT and WUT) and 60 seconds for other commands. Best not to trigger command timeouts. - -v, --verbose
- increase the level of verbosity, (i.e. debug output).
- -V, --version
- print the version string and then exit.
- -w, --wut=SL
-
send a WRITE USING TOKEN (WUT) command with the given scatter list. The
format of SL is given in the NOTES section. This option requires
the --rtf=RTF option to supply the ROD Token. If used without the
--immed option then after the WUT command finishes successfully
this utility will call the RRTI command. When the RRTI command finishes
this utility will exit.
If the --immed option is given this utility will exit after the WUT command finishes. To complete the operation this utility should be invoked again with the --poll option and the same DEVICE.
NOTES
The scatter gather list given to the --pt=GL and --wut=SL options in the simplest case contains a pair a numbers, separated by a comma. The first number is the starting LBA and the second number is the number of blocks (no bigger than 32 bits) to read to or write from that starting LBA. Another pair of numbers can appear after that forming the second element of a scatter gather list. Starting LBAs can be in any order but T10 prohibits any logical block appearing more than once in a scatter gather list.Scatter gather lists can be placed in a file or read from stdin. A file name referring to a file containing a scatter gather list must follow the "@" character (e.g. --pt=@my_sgl.txt"). Reading a list from stdin is indicated by "@-" or "-" (e.g. "--pt=-"). Scatter gather lists in a file have a looser format and can take spaces and tabs as well as a comma as separators. Anything from and including a "#" on a line is ignored.
Both the PT and WUT commands are issued "as is" without checking the Third Party Copy VPD page. The copy manager may well reject these commands (with exit status 51: invalid field in parameter list) if the maximum range descriptors field or the maximum token transfer size field are exceeded.
There is a web page discussing ddptctl and ddpt, XCOPY and ODX at http://sg.danny.cz/sg/ddpt_xcopy_odx.html
EXIT STATUS
The exit status of ddptctl is 0 when it is successful. Otherwise the exit status for this utility is the same as that for ddpt. See the EXIT STATUS section in the ddpt man page.EXAMPLES
First issue a PT command without the --immed option so RRTI is called to complete the operation:
The transfer count (10k + 5k == 15360) indicates the operation was successful and the ROD Token is in the aa.rt file. Now use that ROD Token to write to the same locations on /dev/sdc:
So the copy was successful. Now taking a closer look at the ROD token:
Peripheral Device type: 0x0
Relative initiator port identifier: 0x0
designator_type: NAA,
associated with the addressed logical unit
T10 does not require implementations to supply much of the above (only the ROD type and the token length) so expect to see some empty fields.
To see information about /dev/sdb relevant to ODX, try:
Third Party Copy VPD page:
Block Device ROD Token Limits:
That maximum token transfer size [524288 blocks each 512 bytes gives 256 MB] is the largest size a ROD Token created by /dev/sdb can hold. Use that and show the --immed option on the destination:
To copy larger amounts and/or with a larger number of scatter gather elements (than 8 "range descriptors") use one of the four ODX variants in the ddpt utility.
AUTHORS
Written by Douglas Gilbert.REPORTING BUGS
Report bugs to <dgilbert at interlog dot com>.COPYRIGHT
Copyright © 2014 Douglas GilbertThis software is distributed under a FreeBSD license. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
SEE ALSO
ddpt