1SG3_UTILS(8) SG3_UTILS SG3_UTILS(8)
2
6 sg3_utils - a package of utilities for sending SCSI commands
7
9 sg_* [--dry-run] [--enumerate] [--help] [--hex] [--in=FN] [--inhex=FN]
10 [--maxlen=LEN] [--raw] [--timeout=SECS] [--verbose] [--version]
11 [OTHER_OPTIONS] DEVICE
12
14 sg3_utils is a package of utilities that send SCSI commands to the
15 given DEVICE via a SCSI pass through interface provided by the host
16 operating system.
17 The names of all utilities start with "sg" and most start with "sg_"
19 often followed by the name, or a shortening of the name, of the SCSI
20 command that they send. For example the "sg_verify" utility sends the
21 SCSI VERIFY command. A mapping between SCSI commands and the sg3_utils
22 utilities that issue them is shown in the COVERAGE file. The sg_raw
23 utility can be used to send an arbitrary SCSI command (supplied on the
24 command line) to the given DEVICE.
25 sg_decode_sense can be used to decode SCSI sense data given on the com‐
27 mand line or in a file. sg_raw -vvv will output the T10 name of a given
28 SCSI CDB which is most often 16 bytes or less in length.
29 SCSI draft standards can be found at http://www.t10.org . The standards
31 themselves can be purchased from ANSI and other standards organiza‐
32 tions. A good overview of various SCSI standards can be seen in
33 http://www.t10.org/scsi-3.htm with the SCSI command sets in the upper
34 part of the diagram. The highest level (i.e. most abstract) document is
35 the SCSI Architecture Model (SAM) with SAM-5 being the most recent
36 standard (ANSI INCITS 515-2016) with the most recent draft being SAM-6
37 revision 4 . SCSI commands in common with all device types can be found
38 in SCSI Primary Commands (SPC) of which SPC-4 is the most recent stan‐
39 dard (ANSI INCITS 513-2015). The most recent SPC draft is SPC-5 revi‐
40 sion 21. Block device specific commands (e.g. as used by disks) are in
41 SBC, those for tape drives in SSC, those for SCSI enclosures in SES and
42 those for CD/DVD/BD drives in MMC.
43 It is becoming more common to control ATA disks with the SCSI command
45 set. This involves the translation of SCSI commands to their corre‐
46 sponding ATA equivalents (and that is an imperfect mapping in some
47 cases). The relevant standard is called SCSI to ATA Translation (SAT,
48 SAT-2 and SAT-3) are now standards at INCITS(ANSI) and ISO while SAT-4
49 is at the draft stage. The logic to perform the command translation is
50 often called a SAT Layer or SATL and may be within an operating system,
51 in host bus adapter firmware or in an external device (e.g. associated
52 with a SAS expander). See http://www.t10.org for more information.
53 There is some support for SCSI tape devices but not for their basic
55 operation. The reader is referred to the "mt" utility.
56 There are two generations of command line option usage. The newer util‐
58 ities (written since July 2004) use the getopt_long() function to parse
59 command line options. With that function, each option has two represen‐
60 tations: a short form (e.g. '-v') and a longer form (e.g. '--verbose').
61 If an argument is required then it follows a space (optionally) in the
62 short form and a "=" in the longer form (e.g. in the sg_verify utility
63 '-l 2a6h' and '--lba=2a6h' are equivalent). Note that with
64 getopt_long(), short form options can be elided, for example: '-all' is
65 equivalent to '-a -l -l'. The DEVICE argument may appear after,
66 between or prior to any options.
67 The older utilities, including as sg_inq, sg_logs, sg_modes, sg_opcode,
69 sg_rbuff, sg_readcap, sg_senddiag, sg_start and sg_turs had individual
70 command line processing code typically based on a single "-" followed
71 by one or more characters. If an argument is needed then it follows a
72 "=" ( e.g. '-p=1f' in sg_modes with its older interface). Various
73 options can be elided as long as it is not ambiguous (e.g. '-vv' to
74 increase the verbosity).
75 Over time the command line interface of these older utilities became
77 messy and overloaded with options. So in sg3_utils version 1.23 the
78 command line interface of these older utilities was altered to have
79 both a cleaner getopt_long() interface and their older interface for
80 backward compatibility. By default these older utilities use their
81 getopt_long() based interface. The getopt_long() is a GNU extension
82 (i.e. not yet POSIX certified) but more recent command line utilities
83 tend to use it. That can be overridden by defining the
84 SG3_UTILS_OLD_OPTS environment variable or using '-O' or '--old' as the
85 first command line option. The man pages of the older utilities docu‐
86 ments the details.
87 Several sg3_utils utilities are based on the Unix dd command (e.g.
89 sg_dd) and permit copying data at the level of SCSI READ and WRITE com‐
90 mands. sg_dd is tightly bound to Linux and hence is not ported to other
91 OSes. A more generic utility (than sg_dd) called ddpt in a package of
92 the same name has been ported to other OSes.
93
95 The SG3_UTILS_OLD_OPTS environment variable is explained in the previ‐
96 ous section. It is only for backward compatibility of the command line
97 options for older utilities.
98 The SG3_UTILS_DSENSE environment variable may be set to a number. If
100 that number is non-zero then descriptor sense is set in the SNTL (the
101 small SCSI to NVMe Translation Layer within the underlying library).
102 Several utilities have their own environment variable setting (e.g.
104 sg_persist has SG_PERSIST_IN_RDONLY). See individual utility man pages
105 for more information.
106 There is a Linux specific environment variable called
108 SG3_UTILS_LINUX_NANO that if defined and the sg driver in the system is
109 4.0.30 or later, will show command durations in nanoseconds rather than
110 the default milliseconds. Command durations are typically only shown
111 if --verbose is used 3 or more times. Due to an interface problem (a 32
112 bit integer that should be 64 bits with the benefit of hindsight) the
113 maximum duration that can be represented in nanoseconds is about 4.2
114 seconds. If longer durations may occur then don't define this environ‐
115 ment variable (or undefine it).
116
118 Most disk block devices have names like /dev/sda, /dev/sdb, /dev/sdc,
119 etc. SCSI disks in Linux have always had names like that but in recent
120 Linux kernels it has become more common for many other disks (including
121 SATA disks and USB storage devices) to be named like that. Partitions
122 within a disk are specified by a number appended to the device name,
123 starting at 1 (e.g. /dev/sda1 ).
124 Tape drives are named /dev/st<num> or /dev/nst<num> where <num> starts
126 at zero. Additionally one letter from this list: "lma" may be appended
127 to the name. CD, DVD and BD readers (and writers) are named
128 /dev/sr<num> where <num> start at zero. There are less used SCSI device
129 type names, the dmesg and the lsscsi commands may help to find if any
130 are attached to a running system.
131 There is also a SCSI device driver which offers alternate generic
133 access to SCSI devices. It uses names of the form /dev/sg<num> where
134 <num> starts at zero. The "lsscsi -g" command may be useful in finding
135 these and which generic name corresponds to a device type name (e.g.
136 /dev/sg2 may correspond to /dev/sda). In the lk 2.6 series a block SCSI
137 generic driver was introduced and its names are of the form
138 /dev/bsg/<h:c:t:l> where h, c, t and l are numbers. Again see the lss‐
139 csi command to find the correspondence between that SCSI tuple (i.e.
140 <h:c:t:l>) and alternate device names.
141 Prior to the Linux kernel 2.6 series these utilities could only use
143 generic device names (e.g. /dev/sg1 ). In almost all cases in the Linux
144 kernel 2.6 series, any device name can be used by these utilities.
145 Very little has changed in Linux device naming in the Linux kernel 3
147 and 4 series.
148
150 Storage and related devices can have several device names in Windows.
151 Probably the most common in the volume name (e.g. "D:"). There are also
152 a "class" device names such as "PhysicalDrive<n>", "CDROM<n>" and
153 "TAPE<n>". <n> is an integer starting at 0 allocated in ascending order
154 as devices are discovered (and sometimes rediscovered).
155 Some storage devices have a SCSI lower level device name which starts
157 with a SCSI (pseudo) adapter name of the form "SCSI<n>:". To this is
158 added sub-addressing in the form of a "bus" number, a "target" identi‐
159 fier and a LUN (Logical Unit Number). The "bus" number is also known as
160 a "PathId". These are assembled to form a device name of the form:
161 "SCSI<n>:<bus>,<target>,<lun>". The trailing ",<lun>" may be omitted in
162 which case a LUN of zero is assumed. This lower level device name can‐
163 not often be used directly since Windows blocks attempts to use it if a
164 class driver has "claimed" the device. There are SCSI device types
165 (e.g. Automation/Drive interface type) for which there is no class
166 driver. At least two transports ("bus types" in Windows jargon): USB
167 and IEEE 1394 do not have a "scsi" device names of this form.
168 In keeping with DOS file system conventions, the various device names
170 can be given in upper, lower or mixed case. Since "PhysicalDrive<n>" is
171 tedious to write, a shortened form of "PD<n>" is permitted by all util‐
172 ities in this package.
173 A single device (e.g. a disk) can have many device names. For example:
175 "PD0" can also be "C:", "D:" and "SCSI0:0,1,0". The two volume names
176 reflect that the disk has two partitions on it. Disk partitions that
177 are not recognized by Windows are not usually given a volume name. How‐
178 ever Vista does show a volume name for a disk which has no partitions
179 recognized by it and when selected invites the user to format it (which
180 may be rather unfriendly to other OSes).
181 These utilities assume a given device name is in the Win32 device
183 namespace. To make that explicit "\\.\" can be prepended to the device
184 names mentioned in this section. Beware that backslash is an escape
185 character in Unix like shells and the C programming language. In a
186 shell like Msys (from MinGW) each backslash may need to be typed twice.
187 The sg_scan utility within this package lists out Windows device names
189 in a form that is suitable for other utilities in this package to use.
190
192 SCSI disks have block names of the form /dev/da<num> where <num> is an
193 integer starting at zero. The "da" is replaced by "sa" for SCSI tape
194 drives and "cd" for SCSI CD/DVD/BD drives. Each SCSI device has a cor‐
195 responding pass-through device name of the form /dev/pass<num> where
196 <num> is an integer starting at zero. The "camcontrol devlist" command
197 may be useful for finding out which SCSI device names are available and
198 the correspondence between class and pass-through names.
199
201 SCSI device names below the /dev directory have a form like: c5t4d3s2
202 where the number following "c" is the controller (HBA) number, the num‐
203 ber following "t" is the target number (from the SCSI parallel inter‐
204 face days) and the number following "d" is the LUN. Following the "s"
205 is the slice number which is related to a partition and by convention
206 "s2" is the whole disk.
207 OpenSolaris also has a c5t4d3p2 form where the number following the "p"
209 is the partition number apart from "p0" which is the whole disk. So a
210 whole disk may be referred to as either c5t4d3, c5t4d3s2 or c5t4d3p0 .
211 And these device names are duplicated in the /dev/dsk and /dev/rdsk
213 directories. The former is the block device name and the latter is for
214 "raw" (or char device) access which is what sg3_utils needs. So in
215 OpenSolaris something of the form 'sg_inq /dev/rdsk/c5t4d3p0' should
216 work. If it doesn't work then add a '-vvv' option for more debug
217 information. Trying this form 'sg_inq /dev/dsk/c5t4d3p0' (note "rdsk"
218 changed to "dsk") will result in an "inappropriate ioctl for device"
219 error.
220 The device names within the /dev directory are typically symbolic links
222 to much longer topological names in the /device directory. In Solaris
223 cd/dvd/bd drives seem to be treated as disks and so are found in the
224 /dev/rdsk directory. Tape drives appear in the /dev/rmt directory.
225 There is also a sgen (SCSI generic) driver which by default does not
227 attach to any device. See the /kernel/drv/sgen.conf file to control
228 what is attached. Any attached device will have a device name of the
229 form /dev/scsi/c5t4d3 .
230 Listing available SCSI devices in Solaris seems to be a challenge. "Use
232 the 'format' command" advice works but seems a very dangerous way to
233 list devices. [It does prompt again before doing any damage.] 'devfsadm
234 -Cv' cleans out the clutter in the /dev/rdsk directory, only leaving
235 what is "live". The "cfgadm -v" command looks promising.
236
238 NVMe (or NVM Express) is a relatively new storage transport and command
239 set. The level of abstraction of the NVMe command set is somewhat lower
240 the SCSI command sets, closer to the level of abstraction of ATA (and
241 SATA) command sets. NVMe claims to be designed with flash and modern
242 "solid state" storage in mind, something unheard of when SCSI was orig‐
243 inally developed in the 1980s.
244 The SCSI command sets' advantage is the length of time they have been
246 in place and the existing tools (like these) to support it. Plus SCSI
247 command sets level of abstraction is both and advantage and disadvan‐
248 tage. Recently the NVME-MI (Management Interface) designers decide to
249 use the SCSI Enclosure Services (SES-3) standard "as is" with the addi‐
250 tion of two tunnelling NVME-MI commands: SES Send and SES Receive. This
251 means after the OS interface differences are taken into account, the
252 sg_ses, sg_ses_microcode and sg_senddiag utilities can be used on a
253 NVMe device that supports a newer version of NVME-MI.
254 The NVME-MI SES Send and SES Receive commands correspond to the SCSI
256 SEND DIAGNOSTIC and RECEIVE DIAGNOSTIC RESULTS commands respectively.
257 There are however a few other commands that need to be translated, the
258 most important of which is the SCSI INQUIRY command to the NVMe Iden‐
259 tify controller/namespace. Starting in version 1.43 these utilities
260 contain a small SNTL (SCSI to NVMe Translation Layer) to take care of
261 these details.
262 As a side effect of this "juggling" if the sg_inq utility is used
264 (without the --page= option) on a NVMe DEVICE then the actual NVMe
265 Identifier (controller and possibly namespace) responses are decoded
266 and output. However if 'sg_inq --page=sinq <device>' is given for the
267 same DEVICE then parts of the NVMe Identify controller and namespace
268 response are translated to a SCSI standard INQUIRY response which is
269 then decoded and output.
270 Apart from the special case with the sg_inq, all other utilities in the
272 package assume they are talking to a SCSI device and decode any
273 response accordingly. One easy way for users to see the underlying
274 device is a NVMe device is the standard INQUIRY response Vendor Identi‐
275 fication field of "NVMe " (an 8 character long string with 4 spaces
276 to the right).
277 The following SCSI commands are currently supported by the SNTL
279 library: INQUIRY, MODE SELECT(10), MODE SENSE(10), READ CAPACITY(10 and
280 16), RECEIVE DIAGNOSTIC RESULTS, REQUEST SENSE, REPORT LUNS, REPORT
281 SUPPORTED OPERATION CODES, REPORT SUPPORTED TASK MANAGEMENT FUNCTIONS,
282 SEND DIAGNOSTICS, and TEST UNIT READY.
283
285 To aid scripts that call these utilities, the exit status is set to
286 indicate success (0) or failure (1 or more). Note that some of the
287 lower values correspond to the SCSI sense key values.
288 The exit status values listed below can be given to the sg_decode_sense
290 utility (which is found in this package) as follows:
291 sg_decode_sense --err=<exit_status>
292 and a short explanatory string will be output to stdout.
293 The exit status values are:
295 0 success. Also used for some utilities that wish to return a
297 boolean value for the "true" case (and that no error has
298 occurred). The false case is conveyed by exit status 36.
299 1 syntax error. Either illegal command line options, options with
301 bad arguments or a combination of options that is not permitted.
302 2 the DEVICE reports that it is not ready for the operation
304 requested. The DEVICE may be in the process of becoming ready
305 (e.g. spinning up but not at speed) so the utility may work
306 after a wait. In Linux the DEVICE may be temporarily blocked
307 while error recovery is taking place.
308 3 the DEVICE reports a medium or hardware error (or a blank
310 check). For example an attempt to read a corrupted block on a
311 disk will yield this value.
312 5 the DEVICE reports an "illegal request" with an additional sense
314 code other than "invalid command operation code". This is often
315 a supported command with a field set requesting an unsupported
316 capability. For commands that require a "service action" field
317 this value can indicate that the command with that service
318 action value is not supported.
319 6 the DEVICE reports a "unit attention" condition. This usually
321 indicates that something unrelated to the requested command has
322 occurred (e.g. a device reset) potentially before the current
323 SCSI command was sent. The requested command has not been exe‐
324 cuted by the device. Note that unit attention conditions are
325 usually only reported once by a device.
326 7 the DEVICE reports a "data protect" sense key. This implies some
328 mechanism has blocked writes (or possibly all access to the
329 media).
330 9 the DEVICE reports an illegal request with an additional sense
332 code of "invalid command operation code" which means that it
333 doesn't support the requested command.
334 10 the DEVICE reports a "copy aborted". This implies another com‐
336 mand or device problem has stopped a copy operation. The
337 EXTENDED COPY family of commands (including WRITE USING TOKEN)
338 may return this sense key.
339 11 the DEVICE reports an aborted command. In some cases aborted
341 commands can be retried immediately (e.g. if the transport
342 aborted the command due to congestion).
343 14 the DEVICE reports a miscompare sense key. VERIFY and COMPARE
345 AND WRITE commands may report this.
346 15 the utility is unable to open, close or use the given DEVICE or
348 some other file. The given file name could be incorrect or there
349 may be permission problems. Adding the '-v' option may give more
350 information.
351 17 a SCSI "Illegal request" sense code received with a flag indi‐
353 cating the Info field is valid. This is often a LBA but its
354 meaning is command specific.
355 18 the DEVICE reports a medium or hardware error (or a blank check)
357 with a flag indicating the Info field is valid. This is often a
358 LBA (of the first encountered error) but its meaning is command
359 specific.
360 20 the DEVICE reports it has a check condition but "no sense" and
362 non-zero information in its additional sense codes. Some polling
363 commands (e.g. REQUEST SENSE) can receive this response. There
364 may be useful information in the sense data such as a progress
365 indication.
366 21 the DEVICE reports a "recovered error". The requested command
368 was successful. Most likely a utility will report a recovered
369 error to stderr and continue, probably leaving the utility with
370 an exit status of 0 .
371 22 the DEVICE reports that the current command or its parameters
373 imply a logical block address (LBA) that is out of range. This
374 happens surprisingly often when trying to access the last block
375 on a storage device; either a classic "off by one" logic error
376 or a misreading of the response from READ CAPACITY(10 or 16) in
377 which the address of the last block rather than the number of
378 blocks on the DEVICE is returned. Since LBAs are origin zero
379 they range from 0 to n-1 where n is the number of blocks on the
380 DEVICE, so the LBA of the last block is one less than the total
381 number of blocks.
382 24 the DEVICE reports a SCSI status of "reservation conflict". This
384 means access to the DEVICE with the current command has been
385 blocked because another machine (HBA or SCSI "initiator") holds
386 a reservation on this DEVICE. On modern SCSI systems this is
387 related to the use of the PERSISTENT RESERVATION family of com‐
388 mands.
389 25 the DEVICE reports a SCSI status of "condition met". Currently
391 only the PRE-FETCH command (see SBC-4) yields this status.
392 26 the DEVICE reports a SCSI status of "busy". SAM-6 defines this
394 status as the logical unit is temporarily unable to process a
395 command. It is recommended to re-issue the command.
396 27 the DEVICE reports a SCSI status of "task set full".
398 28 the DEVICE reports a SCSI status of "ACA active". ACA is "auto
400 contingent allegiance" and is seldom used.
401 29 the DEVICE reports a SCSI status of "task aborted". SAM-5 says:
403 "This status shall be returned if a command is aborted by a com‐
404 mand or task management function on another I_T nexus and the
405 Control mode page TAS bit is set to one".
406 31 error involving two or more command line options. They may be
408 contradicting, select an unsupported mode, or a required option
409 (given the context) is missing.
410 32 there is a logic error in the utility. It corresponds to code
412 comments like "shouldn't/can't get here". Perhaps the author
413 should be informed.
414 33 the command sent to DEVICE has timed out.
416 34 this is a Windows only exit status and indicates that the Win‐
418 dows error number (32 bits) cannot meaningfully be mapped to an
419 equivalent Unix error number returned as the exit status (7
420 bits).
421 36 no error has occurred plus the utility wants to convey a boolean
423 value of false. The corresponding true value is conveyed by a 0
424 exit status.
425 40 the command sent to DEVICE has received an "aborted command"
427 sense key with an additional sense code of 0x10. This group is
428 related to problems with protection information (PI or DIF). For
429 example this error may occur when reading a block on a drive
430 that has never been written (or is unmapped) if that drive was
431 formatted with type 1, 2 or 3 protection.
432 41 the command sent to DEVICE has received an "aborted command"
434 sense key with an additional sense code of 0x10 (as with error
435 code) plus a flag indicating the Info field is valid.
436 48 this is an internal message indicating a NVMe status field (SF)
438 is other than zero after a command has been executed (i.e. some‐
439 thing went wrong). Work in this area is currently experimental.
440 49 low level driver reports a response's residual count (i.e. num‐
442 ber of bytes actually received by HBA is 'requested_bytes -
443 residual_count') that is
444 50 OS system calls that fail often return a small integer number to
446 help. In Unix these are called "errno" values where 0 implies no
447 error. These error codes set aside 51 to 96 for mapping these
448 errno values but that may not be sufficient. Higher errno values
449 that cannot be mapped are all mapped to this value (i.e. 50).
450 Note that an errno value of 0 is mapped to error code 0.
451 50 + <os_error_number>
453 OS system calls that fail often return a small integer number to
454 help indicate what the error is. For example in Unix the inabil‐
455 ity of a system call to allocate memory returns (in 'errno')
456 ENOMEM which often is associated with the integer 12. So 62
457 (i.e. '50 + 12') may be returned by a utility in this case. It
458 is also possible that a utility in this package reports
459 50+ENOMEM when it can't allocate memory, not necessarily from an
460 OS system call. In recent versions of Linux the file showing the
461 mapping between symbolic constants (e.g. ENOMEM) and the corre‐
462 sponding integer is in the kernel source code file:
463 include/uapi/asm-generic/errno-base.h
464 Note that errno values that are greater than or equal to 47 can‐
465 not fit in range provided. Instead they are all mapped to 50 as
466 discussed in the previous entry.
467 97 a SCSI command response failed sanity checks.
469 98 the DEVICE reports it has a check condition but the error
471 doesn't fit into any of the above categories.
472 99 any errors that can't be categorized into values 1 to 98 may
474 yield this value. This includes transport and operating system
475 errors after the command has been sent to the device.
476 100-125
478 these error codes are used by the ddpt utility which uses the
479 sg3_utils library. They are mainly specialized error codes asso‐
480 ciated with offloaded copies.
481 126 the utility was found but could not be executed. That might
483 occur if the executable does not have execute permissions.
484 127 This is the exit status for utility not found. That might occur
486 when a script calls a utility in this package but the PATH envi‐
487 ronment variable has not been properly set up, so the script
488 cannot find the executable.
489 128 + <signum>
491 If a signal kills a utility then the exit status is 128 plus the
492 signal number. For example if a segmentation fault occurs then a
493 utility is typically killed by SIGSEGV which according to 'man 7
494 signal' has an associated signal number of 11; so the exit sta‐
495 tus will be 139 .
496 255 the utility tried to yield an exit status of 255 or larger. That
498 should not happen; given here for completeness.
499 Most of the error conditions reported above will be repeatable (an
501 example of one that is not is "unit attention") so the utility can be
502 run again with the '-v' option (or several) to obtain more information.
503
505 Arguments to long options are mandatory for short options as well. In
506 the short form an argument to an option uses zero or more spaces as a
507 separator (i.e. the short form does not use "=" as a separator).
508 If an option takes a numeric argument then that argument is assumed to
510 be decimal unless otherwise indicated (e.g. with a leading "0x", a
511 trailing "h" or as noted in the usage message).
512 Some options are used uniformly in most of the utilities in this pack‐
514 age. Those options are listed below. Note that there are some excep‐
515 tions.
516 -d, --dry-run
518 utilities that can cause lots of user data to be lost or over‐
519 written sometimes have a --dry-run option. Device modifying
520 actions are typically bypassed (or skipped) to implement a pol‐
521 icy of "do no harm". This allows complex command line invoca‐
522 tions to be tested before the action required (e.g. format a
523 disk) is performed. The --dry-run option has become a common
524 feature of many command line utilities (e.g. the Unix 'patch'
525 command), not just those from this package.
526 Note that most hyphenated option names in this package also can
527 be given with an underscore rather than a hyphen (e.g.
528 --dry_run).
529 -e, --enumerate
531 some utilities (e.g. sg_ses and sg_vpd) store a lot of informa‐
532 tion in internal tables. This option will output that informa‐
533 tion in some readable form (e.g. sorted by an acronym or by page
534 number) then exit. Note that with this option DEVICE is ignored
535 (as are most other options) and no SCSI IO takes place, so the
536 invoker does not need any elevated permissions.
537 -h, -?, --help
539 output the usage message then exit. In a few older utilities the
540 '-h' option requests hexadecimal output. In these cases the '-?'
541 option will output the usage message then exit.
542 -H, --hex
544 for SCSI commands that yield a non-trivial response, print out
545 that response in ASCII hexadecimal. To produce hexadecimal that
546 can be parsed by other utilities (e.g. without a relative
547 address to the left and without trailing ASCII) use this option
548 three or four times.
549 -i, --in=FN
551 many SCSI commands fetch a significant amount of data (returned
552 in the data-in buffer) which several of these utilities decode
553 (e.g. sg_vpd and sg_logs). To separate the two steps of fetching
554 the data from a SCSI device and then decoding it, this option
555 has been added. The first step (fetching the data) can be done
556 using the --hex or --raw option and redirecting the command line
557 output to a file (often done with ">" in Unix based operating
558 systems). The difference between --hex and --raw is that the
559 former produces output in ASCII hexadecimal while --raw produces
560 its output in "raw" binary.
561 The second step (i.e. decoding the SCSI response data now held
562 in a file) can be done using this --in=FN option where the file
563 name is FN. If "-" is used for FN then stdin is assumed, again
564 this allows for command line redirection (or piping). That file
565 (or stdin) is assumed to contain ASCII hexadecimal unless the
566 --raw option is also given in which case it is assumed to be
567 binary. Notice that the meaning of the --raw option is "flipped"
568 when used with --in=FN to act on the input, typically it acts on
569 the output data.
570 Since the structure of the data returned by SCSI commands varies
571 considerably then the usage information or the manpage of the
572 utility being used should be checked. In some cases --hex may
573 need to be used multiple times (and is more conveniently given
574 as '-HH' or '-HHH).
575 -i, --inhex=FN
577 This option has the same or similar functionality as --in=FN.
578 And perhaps 'inhex' is more descriptive since by default, ASCII
579 hexadecimal is expected in the contents of file: FN. Alterna‐
580 tively the short form option may be -I or -X. See the "FORMAT OF
581 FILES CONTAINING ASCII HEX" section below for more information.
582 -m, --maxlen=LEN
584 several important SCSI commands (e.g. INQUIRY and MODE SENSE)
585 have response lengths that vary depending on many factors, only
586 some of which these utilities take into account. The maximum
587 response length is typically specified in the 'allocation
588 length' field of the cdb. In the absence of this option, several
589 utilities use a default allocation length (sometimes recommended
590 in the SCSI draft standards) or a "double fetch" strategy. See
591 sg_logs(8) for its description of a "double fetch" strategy.
592 These techniques are imperfect and in the presence of faulty
593 SCSI targets can cause problems (e.g. some USB mass storage
594 devices freeze if they receive an INQUIRY allocation length
595 other than 36). Also use of this option disables any "double
596 fetch" strategy that may have otherwise been used.
597 -r, --raw
599 for SCSI commands that yield a non-trivial response, output that
600 response in binary to stdout. If any error messages or warning
601 are produced they are usually sent to stderr so as to not inter‐
602 fere with the output from this option.
603 Some utilities that consume data to send to the DEVICE along
604 with the SCSI command, use this option. Alternatively the
605 --in=FN option causes DEVICE to be ignored and the response data
606 (to be decoded) fetched from a file named FN. In these cases
607 this option may indicate that binary data can be read from stdin
608 or from a nominated file (e.g. FN).
609 -t, --timeout=SECS
611 utilities that issue potentially long-running SCSI commands
612 often have a --timeout=SECS option. This typically instructs the
613 operating system to abort the SCSI command in question once the
614 timeout expires. Aborting SCSI commands is typically a messy
615 business and in the case of format like commands may leave the
616 device in a "format corrupt" state requiring another long-run‐
617 ning re-initialization command to be sent. The argument, SECS,
618 is usually in seconds and the short form of the option may be
619 something other than -t since the timeout option was typically
620 added later as storage devices grew in size and initialization
621 commands took longer. Since many utilities had relatively long
622 internal command timeouts before this option was introduced, the
623 actual command timeout given to the operating systems is the
624 higher of the internal timeout and SECS.
625 Many long running SCSI commands have an IMMED bit which causes
626 the command to finish relatively quickly but the initialization
627 process to continue. In such cases the REQUEST SENSE command can
628 be used to monitor progress with its progress indication field
629 (see the sg_requests and sg_turs utilities). Utilities that
630 send such SCSI command either have an --immed option or a --wait
631 option which is the logical inverse of the "immediate" action.
632 -v, --verbose
634 increase the level of verbosity, (i.e. debug output). Can be
635 used multiple times to further increase verbosity. The addi‐
636 tional output caused by this option is almost always sent to
637 stderr.
638 -V, --version
640 print the version string and then exit. Each utility has its own
641 version number and date of last code change.
642
644 Many utilities have command line options that take numeric arguments.
645 These numeric arguments can be large values (e.g. a logical block
646 address (LBA) on a disk) and can be inconvenient to enter in the
647 default decimal representation. So various other representations are
648 permitted.
649 Multiplicative suffixes are accepted. They are one, two or three letter
651 strings appended directly after the number to which they apply:
652 c C *1
654 w W *2
655 b B *512
656 k K KiB *1024
657 KB kB *1000
658 m M MiB *1048576
659 MB mB *1000000
660 g G GiB *(2^30)
661 GB gB *(10^9)
662 t T TiB *(2^40)
663 TB *(10^12)
664 p P PiB *(2^50)
665 PB *(10^15)
666 An example is "2k" for 2048. The large tera and peta suffixes are only
668 available for numeric arguments that might require 64 bits to represent
669 internally.
670 These multiplicative suffixes are compatible with GNU's dd command
672 (since 2002) which claims compliance with SI and with IEC 60027-2.
673 A suffix of the form "x<n>" multiplies the preceding number by <n>. An
675 example is "2x33" for "66". The left argument cannot be '0' as '0x'
676 will be interpreted as hexadecimal number prefix (see below). The left
677 argument to the multiplication must end in a hexadecimal digit (i.e. 0
678 to f) and the whole expression cannot have any embedded whitespace
679 (e.g. spaces). An ugly example: "0xfx0x2" for 30.
680 A suffix of the form "+<n>" adds the preceding number to <n>. An exam‐
682 ple is "3+1k" for "1027". The left argument to the addition must end in
683 a hexadecimal digit (i.e. 0 to f) and the whole expression cannot have
684 any embedded whitespace (e.g. spaces). Another example: "0xf+0x2" for
685 17.
686 Alternatively numerical arguments can be given in hexadecimal. There
688 are two syntaxes. The number can be preceded by either "0x" or "0X" as
689 found in the C programming language. The second hexadecimal representa‐
690 tion is a trailing "h" or "H" as found in (storage) standards. When hex
691 numbers are given, multipliers cannot be used. For example the decimal
692 value "256" can be given as "0x100" or "100h".
693
695 Such a file is assumed to contain a sequence of one or two digit ASCII
696 hexadecimal values separated by whitespace. "Whitespace consists of
697 either spaces, tabs, blank lines, or any combination thereof". Each one
698 or two digit ASCII hex pair is decoded into a byte (i.e. 8 bits). The
699 following will be decoded to valid (ascending valued) bytes: '0', '01',
700 '3', 'c', 'F', '4a', 'cC', 'ff'. Lines containing only whitespace are
701 ignored. The contents of any line containing a hash mark ('#') is
702 ignored from that point until the end of that line. Users are encour‐
703 aged to use hash marks to introduce comments in hex files. The author
704 uses the extension'.hex' on such files. Examples can be found in the
705 'inhex' directory.
706
708 There are two standardized methods for downloading microcode (i.e.
709 device firmware) to a SCSI device. The more general way is with the
710 SCSI WRITE BUFFER command, see the sg_write_buffer utility. SCSI enclo‐
711 sures have their own method based on the Download microcode con‐
712 trol/status diagnostic page, see the sg_ses_microcode utility.
713
715 There are several bash shell scripts in the 'scripts' subdirectory that
716 invoke compiled utilities (e.g. sg_readcap). Several of the scripts
717 start with 'scsi_' rather than 'sg_'. One purpose of these scripts is
718 to call the same utility (e.g. sg_readcap) on multiple devices. Most of
719 the basic compiled utilities only allow one device as an argument. Some
720 distributions install these scripts in a more visible directory (e.g.
721 /usr/bin). Some of these scripts have man page entries. See the README
722 file in the 'scripts' subdirectory.
723 There is some example C code plus examples of complex invocations in
725 the 'examples' subdirectory. There is also a README file. The example C
726 may be a simpler example of how to use a SCSI pass-through in Linux
727 than the main utilities (found in the 'src' subdirectory). This is due
728 to the fewer abstraction layers (e.g. they don't worry the MinGW in
729 Windows may open a file in text rather than binary mode).
730 Some utilities that the author has found useful have been placed in the
732 'utils' subdirectory.
733
735 There is a web page discussing this package at
736 http://sg.danny.cz/sg/sg3_utils.html . The device naming used by this
737 package on various operating systems is discussed at:
738 http://sg.danny.cz/sg/device_name.html . There is a git code mirror at
739 https://github.com/hreinecke/sg3_utils . The principle code repository
740 uses subversion and is on the author's equipment. The author keeps
741 track of this via the subversion revision number which is an ascending
742 integer (currently at 774 for this package). The github mirror gets
743 updated periodically from the author's repository. Depending on the
744 time of update, the above Downloads section at sg.danny.cz may be more
745 up to date than the github mirror.
746
748 Written by Douglas Gilbert. Some utilities have been contributed, see
749 the CREDITS file and individual source files (in the 'src' directory).
750
752 Report bugs to <dgilbert at interlog dot com>.
753
755 Copyright © 1999-2020 Douglas Gilbert
756 Some utilities are distributed under a GPL version 2 license while oth‐
757 ers, usually more recent ones, are under a FreeBSD license. The files
758 that are common to almost all utilities and thus contain the most reus‐
759 able code, namely sg_lib.[hc], sg_cmds_basic.[hc] and
760 sg_cmds_extra.[hc] are under a FreeBSD license. There is NO warranty;
761 not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
762
764 sdparm(sdparm), ddpt(ddpt), lsscsi(lsscsi), dmesg(1), mt(1)
765sg3_utils-1.45 February 2020 SG3_UTILS(8)