1SG_WRITE_BUFFER(8) SG3_UTILS SG_WRITE_BUFFER(8)
2
6 sg_write_buffer - send SCSI WRITE BUFFER commands
7
9 sg_write_buffer [--bpw=CS] [--dry-run] [--help] [--id=ID] [--in=FILE]
10 [--length=LEN] [--mode=MO] [--offset=OFF] [--read-stdin] [--skip=SKIP]
11 [--specific=MS] [--timeout=TO] [--verbose] [--version] DEVICE
12
14 Sends one or more SCSI WRITE BUFFER commands to DEVICE, along with data
15 provided by the user. In some cases no data is required, or data can be
16 read from the file given in the --in=FILE option, or data is read from
17 stdin when either --read-stdin or --in=- is given.
18 Some WRITE BUFFER command variants do not have associated data to send
20 to the device. For example "activate_mc" activates deferred microcode
21 that was sent via prior WRITE BUFFER commands. There is a different
22 method used to download microcode to SES devices, see the
23 sg_ses_microcode utility.
24
26 Arguments to long options are mandatory for short options as well. The
27 options are arranged in alphabetical order based on the long option
28 name.
29 -b, --bpw=CS
31 where CS is the chunk size in bytes. This will be the maximum
32 number of bytes sent per WRITE BUFFER command. So if CS is less
33 than the effective length then multiple WRITE BUFFER commands
34 are sent, each taking the next chunk from the read data and
35 increasing the buffer offset field in the WRITE BUFFER command
36 by the appropriate amount. The default is a chunk size of 0
37 which is interpreted as a very large number hence only one WRITE
38 BUFFER command will be sent. This option should only be used
39 with modes that "download microcode, with offsets ..."; namely
40 either mode 0x6, 0x7, 0xd or 0xe.
41 The number in CS can optionally be followed by ",act" or ",acti‐
42 vate". In this case after WRITE BUFFER commands have been sent
43 until the effective length is exhausted another WRITE BUFFER
44 command with its mode set to "Activate deferred microcode mode"
45 [mode 0xf] is sent.
46 -d, --dry-run
48 Do all the command line processing and sanity checks including
49 reading the input file. However at the point where a WRITE BUF‐
50 FER SCSI command(s) would be sent, step over that call and
51 assume it completed without errors and continue. DEVICE is still
52 opened but can be /dev/null (in Unix). It is recommended to use
53 --verbose with this option to get an overview of what would have
54 happened.
55 -h, --help
57 output the usage message then exit. If used multiple times also
58 prints the mode names and their acronyms.
59 -i, --id=ID
61 this option sets the buffer id field in the cdb. ID is a value
62 between 0 (default) and 255 inclusive.
63 -I, --in=FILE
65 read data from file FILE that will be sent with the WRITE BUFFER
66 command. If FILE is '-' then stdin is read until an EOF is
67 detected (this is the same action as --read-stdin). Data is read
68 from the beginning of FILE except in the case when it is a regu‐
69 lar file and the --skip=SKIP option is given.
70 -l, --length=LEN
72 where LEN is the length, in bytes, of data to be written to the
73 device. If not given (and the length cannot be deduced from
74 --in=FILE or --read-stdin) then defaults to zero. If the option
75 is given and the length deduced from --in=FILE or --read-stdin
76 is less (or no data is provided), then bytes of 0xff are used as
77 fill bytes.
78 -m, --mode=MO
80 this option sets the MODE field in the cdb. MO is a value
81 between 0 (default) and 31 inclusive. Alternatively an abbrevia‐
82 tion can be given. See the MODES section below. To list the
83 available mode abbreviations at run time give an invalid one
84 (e.g. '--mode=xxx') or use the '-hh' option.
85 -o, --offset=OFF
87 this option sets the BUFFER OFFSET field in the cdb. OFF is a
88 value between 0 (default) and 2**24-1 . It is a byte offset.
89 -r, --read-stdin
91 read data from stdin until an EOF is detected. This data is sent
92 with the WRITE BUFFER command to DEVICE. The action of this
93 option is the same as using '--in=-'. Previously this option's
94 long name was --raw and it may still be used for backward com‐
95 patibility.
96 -s, --skip=SKIP
98 this option is only active when --in=FILE is given and FILE is a
99 regular file, rather than stdin. Data is read starting at byte
100 offset SKIP to the end of file (or the amount given by
101 --length=LEN). If not given the byte offset defaults to 0 (i.e.
102 the start of the file).
103 -S, --specific=MS
105 MS is the MODE SPECIFIC field in the cdb. This is a 3-bit field
106 so the values 0 to 7 are accepted. This field was introduced in
107 SPC-4 revision 32 and can be used to specify additional events
108 that activate deferred microcode (when MO is 0xD).
109 -t, --timeout=TO
111 TO is the command timeout (in seconds) for each WRITE BUFFER
112 command issued by this utility. Its default value is 300 seconds
113 (5 minutes) and should only be altered if this is not suffi‐
114 cient.
115 -v, --verbose
117 increase the level of verbosity, (i.e. debug output).
118 -V, --version
120 print the version string and then exit.
121
123 Following is a list of WRITE BUFFER command settings for the MODE
124 field. First is an acronym accepted by the MO argument of this util‐
125 ity. Following the acronym in square brackets are the corresponding
126 decimal and hex values that may also be given for MO. The following are
127 listed in numerical order.
128 hd [0, 0x0]
130 Combined header and data (obsolete in SPC-4).
131 vendor [1, 0x1]
133 Vendor specific.
134 data [2, 0x2]
136 Data (was called "Write Data" in SPC-3).
137 dmc [4, 0x4]
139 Download microcode and activate (was called "Download microcode"
140 in SPC-3).
141 dmc_save [5, 0x5]
143 Download microcode, save, and activate (was called "Download
144 microcode and save" in SPC-3).
145 dmc_offs [6, 0x6]
147 Download microcode with offsets and activate (was called "Down‐
148 load microcode with offsets" in SPC-3).
149 dmc_offs_save [7, 0x7]
151 Download microcode with offsets, save, and activate (was called
152 "Download microcode with offsets and save" in SPC-3).
153 echo [10, 0xa]
155 Write data to echo buffer (was called "Echo buffer" in SPC-3).
156 dmc_offs_ev_defer [13, 0xd]
158 Download microcode with offsets, select activation events, save,
159 and defer activate (introduced in SPC-4).
160 dmc_offs_defer [14, 0xe]
162 Download microcode with offsets, save, and defer activate
163 (introduced in SPC-4).
164 activate_mc [15, 0xf]
166 Activate deferred microcode (introduced in SPC-4).
167 en_ex [26, 0x1A]
169 Enable expander communications protocol and Echo buffer (obso‐
170 lete in SPC-4).
171 dis_ex [27, 0x1B]
173 Disable expander communications protocol (obsolete in SPC-4).
174 deh [28, 0x1C]
176 Download application client error history (was called "Download
177 application log" in SPC-3).
178
180 If no --length=LEN is given this utility reads up to 8 MiB of data from
181 the given file FILE (or stdin). If a larger amount of data is required
182 then the --length=LEN option should be given.
183 The user should be aware that most operating systems have limits on the
185 amount of data that can be sent with one SCSI command. In Linux this
186 depends on the pass through mechanism used (e.g. block SG_IO or the sg
187 driver) and various setting in sysfs in the Linux lk 2.6/3 series (e.g.
188 /sys/block/sda/queue/max_sectors_kb). Devices (i.e. logical units) also
189 typically have limits on the maximum amount of data they can handle in
190 one command. These two limitations suggest that modes containing the
191 word "offset" together with the --bpw=CS option are required as
192 firmware files get larger and larger. And CS can be quite small, for
193 example 4096 bytes, resulting in many WRITE BUFFER commands being sent.
194 Attempting to download a microcode/firmware file that is too large may
196 cause an error to occur in the pass-through layer (i.e. before the SCSI
197 command is issued). In Linux such error reports can be obscure as in
198 "pass through os error invalid argument". FreeBSD reports such errors
199 well to the machine's console but returns a cryptic error message to
200 this utility.
201 Downloading incorrect microcode into a device has the ability to render
203 that device inoperable. One would hope that the device vendor verifies
204 the data before activating it. If the SCSI WRITE BUFFER command is
205 given values in its cdb (e.g. LEN) that are inappropriate (e.g. too
206 large) then the device should respond with a sense key of ILLEGAL
207 REQUEST and an additional sense code of INVALID FIELD in CDB. If a
208 WRITE BUFFER command (or a sequence of them) fails due to device vendor
209 verification checks then it should respond with a sense key of ILLEGAL
210 REQUEST and an additional sense code of COMMAND SEQUENCE ERROR.
211 All numbers given with options are assumed to be decimal. Alterna‐
213 tively numerical values can be given in hexadecimal preceded by either
214 "0x" or "0X" (or has a trailing "h" or "H").
215
217 The following sends new firmware to an enclosure. Sending a 1.5 MB file
218 in one WRITE BUFFER command caused the enclosure to lock up temporarily
219 and did not update the firmware. Breaking the firmware file into 4 KB
220 chunks (an educated guess) was more successful:
221 sg_write_buffer -b 4k -m dmc_offs_save -I firmware.bin /dev/sg4
223 The firmware update occurred in the following enclosure power cycle.
225 With a modern enclosure the Extended Inquiry VPD page gives indications
226 in which situations a firmware upgrade will take place.
227
229 The exit status of sg_write_buffer is 0 when it is successful. Other‐
230 wise see the sg3_utils(8) man page.
231
233 Written by Luben Tuikov and Douglas Gilbert.
234
236 Report bugs to <dgilbert at interlog dot com>.
237
239 Copyright © 2006-2018 Luben Tuikov and Douglas Gilbert
240 This software is distributed under a FreeBSD license. There is NO war‐
241 ranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR‐
242 POSE.
243
245 sg_read_buffer, sg_ses_microcode(sg3_utils)
246sg3_utils-1.45 November 2018 SG_WRITE_BUFFER(8)