1SG_PERSIST(8) SG3_UTILS SG_PERSIST(8)
2
6 sg_persist - use SCSI PERSISTENT RESERVE command to access registra‐
7 tions and reservations
8
10 sg_persist [OPTIONS] DEVICE
11 sg_persist [OPTIONS] --device=DEVICE
13 sg_persist --help | --version
15
17 This utility allows Persistent reservations and registrations to be
18 queried and changed. Persistent reservations and registrations are
19 queried by sub-commands (called "service actions" in SPC-4) of the SCSI
20 PERSISTENT RESERVE IN (PRIN) command. Persistent reservations and reg‐
21 istrations are changed by sub-commands of the SCSI PERSISTENT RESERVE
22 OUT (PROUT) command.
23 There is a two stage process to obtain a persistent reservation. First
25 an application (an I_T nexus in standard's jargon) must register a
26 reservation key. If that is accepted (and it should be unless some
27 other I_T nexus has registered that key) then the application can try
28 and reserve the device. The reserve operation must specify the reser‐
29 vation key and a "type" (see the --prout-type=TYPE option).
30 It is relatively safe to query the state of Persistent reservations and
32 registrations. With no options this utility defaults to the READ KEYS
33 sub-command of the PRIN command. Other PRIN sub-commands are READ
34 RESERVATION, REPORT CAPABILITIES and READ FULL STATUS.
35 Before trying to change Persistent reservations and registrations users
37 should be aware of what they are doing. The relevant sections of the
38 SCSI Primary Commands document (i.e. SPC-4 whose most recent draft is
39 revision 20 dated 22 May 2009) are sections 5.7 (titled "Reserva‐
40 tions"), 6.13 (for the PRIN command) and 6.14 (for the PROUT command).
41 To safeguard against accidental use, the --out option must be given
42 when a PROUT sub-command (e.g. --register) is used.
43 The older SCSI RESERVE and RELEASE commands (both 6 and 10 byte vari‐
45 ants) are not supported by this utility. In SPC-3, RESERVE and RELEASE
46 are deprecated, replaced by Persistent Reservations. RESERVE and
47 RELEASE have been removed from SPC-4 and Annex B is provided showing
48 how to convert to persistent reservation commands. See a utility called
49 'scsires' for support of the SCSI RESERVE and RELEASE commands.
50 The DEVICE is required by all variants of this utility apart from
52 --help. The DEVICE can be given either as an argument (typically but
53 not necessarily the last one) or via the --device=DEVICE option.
54 SPC-4 does not use the term "sub-command". It uses the term "service
56 action" for this and for part of a field's name in the parameter block
57 associated with the PROUT command (i.e. "service action reservation
58 key"). To lessen the potential confusion the term "sub-command" has
59 been introduced.
60
62 Arguments to long options are mandatory for short options as well. The
63 following options are sorted in alphabetical order, based on their long
64 option name.
65 -l, --alloc-length=LEN
67 specify the allocation length of the PRIN command. LEN is a hex
68 value. By default this value is set to the size of the data-in
69 buffer (8192). This parameter is of use for verification that
70 response to PRIN commands with various allocation lengths is per
71 section 4.3.5.6 of SPC-4 revision 18. Valid LEN values are
72 0-8192.
73 -C, --clear
75 Clear is a sub-command of the PROUT command. It releases the
76 persistent reservation (if any) and clears all registrations
77 from the device. It is required to supply a reservation key that
78 is registered for this I_T_L nexus (identified by
79 --param-rk=RK).
80 -d, --device=DEVICE
82 DEVICE to send SCSI commands to. The DEVICE can either be pro‐
83 vided via this option or via a freestanding argument. For exam‐
84 ple, these two: 'sg_persist --device=/dev/sg2' and 'sg_persist
85 /dev/sg2' are equivalent.
86 -h, --help
88 output a usage message.
89 -H, --hex
91 the response to a valid PRIN sub-command will be output in hexa‐
92 decimal. By default (i.e. without this option) if the PRIN
93 sub-command is recognised then the response will be decoded as
94 per SPC-4.
95 -i, --in
97 specify that a SCSI PERSISTENT RESERVE IN command is required.
98 This is the default.
99 -n, --no-inquiry
101 the default action is to do a standard SCSI INQUIRY command and
102 output make, product and revision strings plus the peripheral
103 device type prior to executing a PRIN or PROUT command. With
104 this option the INQUIRY command is skipped.
105 -o, --out
107 specify that a SCSI PERSISTENT RESERVE OUT command is required.
108 -Y, --param-alltgpt
110 set the 'all target ports' (ALL_TG_PT) flag in the parameter
111 block of the PROUT command. Only relevant for 'register' and
112 'register and ignore existing key' sub-commands.
113 -Z, --param-aptpl
115 set the 'activate persist through power loss' (APTPL) flag in
116 the parameter block of the PROUT command. Relevant for 'regis‐
117 ter', 'register and ignore existing key' and 'register and move'
118 sub-commands.
119 -K, --param-rk=RK
121 specify the reservation key found in the parameter block of the
122 PROUT command. RK is assumed to be hex (up to 8 bytes long).
123 Default value is 0. This option is needed by most PROUT sub-com‐
124 mands.
125 -S, --param-sark=SARK
127 specify the service action reservation key found in the parame‐
128 ter block of the PROUT command. SARK is assumed to be hex (up to
129 8 bytes long). Default value is 0. This option is needed by
130 some PROUT sub-commands.
131 -P, --preempt
133 Preempt is a sub-command of the PROUT command. Preempts the
134 existing persistent reservation (identified by
135 --param-sark=SARK) with the registration key that is registered
136 for this I_T_L nexus (identified by --param-rk=RK). If a new
137 reservation is establised as a result of the preemption then the
138 supplied --prout-type=TYPE is used as the type for this new
139 reservation.
140 -A, --preempt-abort
142 Preempt and Abort is a sub-command of the PROUT command. Pre‐
143 empts the existing persistent reservation (identified by
144 --param-sark=SARK) with the registration key that is registered
145 for this I_T_L nexus (identified by --param-rk=RK). If a new
146 reservation is establised as a result of the preemption then the
147 supplied --prout-type=TYPE is used as the type for this new
148 reservation. ACA and other pending tasks are aborted.
149 -T, --prout-type=TYPE
151 specify the PROUT command's 'type' argument. Required by the
152 'register-move', 'reserve', 'release' and 'preempt (and abort)'
153 sub-commands. Valid TYPE values: 1-> write exclusive, 3-> exclu‐
154 sive access, 5-> write exclusive - registrants only, 6-> exclu‐
155 sive access - registrants only, 7-> write exclusive - all regis‐
156 trants, 8-> exclusive access - all registrants. Default value is
157 0 (which is an invalid type). Each "persistent reservation type"
158 is explained in more detail in a subsection of that name in the
159 read reservation section of the PRIN command (section 6.13.3.4
160 of SPC-4 revision 9).
161 -s, --read-full-status
163 Read Full Status is a sub-command of the PRIN command. For each
164 registration with the given SCSI device, it lists the reserva‐
165 tion key and associated information. TransportIDs, if supplied
166 in the response, are decoded.
167 -k, --read-keys
169 Read Keys is a sub-command of the PRIN command. Lists all the
170 reservation keys registered (i.e. registrations) with the given
171 SCSI device. This is the default sub-command for the SCSI PRIN
172 command.
173 -r, --read-reservation
175 Read Reservation is a sub-command of the PRIN command. List
176 information about the current holder of the reservation on the
177 DEVICE. If there is no current reservation this will be noted.
178 Information about the current holder of the reservation includes
179 its reservation key, scope and type.
180 -s, --read-status
182 same as --read-full-status.
183 -G, --register
185 Register is a sub-command of the PROUT command. It has 3 differ‐
186 ent actions depending on associated parameters. a) add a new
187 registration with '--param-rk=0' and '--param-sark=<new_rk>'; b)
188 Change an existing registration with '--param-rk=<old_rk>' and
189 '--param-sark=<new_rk>'; or c) Delete an existing registration
190 with '--param-rk=<old_rk>' and '--param-sark=0'.
191 -I, --register-ignore
193 Register and Ignore Existing Key is a sub-command of the PROUT
194 command. Similar to --register except that when changing a
195 reservation key the old key is not specified. The
196 '--param-sark=<new_rk>' option should also be given.
197 -M, --register-move
199 register (another initiator) and move (the reservation held by
200 the current initiator to that other initiator) is a sub-command
201 of the PROUT command. It requires the transportID of the other
202 initiator. [The standard uses the term I_T nexus but the point
203 to stress is that there are two initiators (the one sending this
204 command and another one) but only one logical unit.] The
205 --prout-type=TYPE and --param-rk=RK options need to match that
206 of the existing reservation while --param-sark=SARK option spec‐
207 ifies the reservation key of the new (i.e. destination) regis‐
208 tration.
209 -Q, --relative-target-port=RTPI
211 relative target port identifier that reservation is to be moved
212 to by PROUT 'register and move' sub-command. RTPI is assumed to
213 be hex in the range 0 to ffff inclusive. Defaults to 0 .
214 -L, --release
216 Release is a sub-command of the PROUT command. It releases the
217 current persistent reservation. The --prout-type=TYPE and
218 --param-rk=RK options, matching the reservation, must also be
219 specified.
220 -c, --report-capabilities
222 Report Capabilities is a sub-command of the PRIN command. It
223 lists information about the aspects of persistent reservations
224 that the DEVICE supports.
225 -R, --reserve
227 Reserve is a sub-command of the PROUT command. It creates a new
228 persistent reservation (if permitted). The --prout-type=TYPE and
229 --param-rk=RK options must also be specified.
230 -X, --transport-id=TIDS
232 The TIDS argument can take one of several forms. It can be a
233 comma (or single space) separated list of ASCII hex bytes repre‐
234 senting a single TransportID as defined in SPC-4. They are usu‐
235 ally 24 bytes long apart from in iSCSI. The TIDS argument may be
236 a transport specific form (e.g. "sas,5000c50005b32001"). The
237 TIDS argument may be "-" in which case one or more TransportIDs
238 can be read from stdin. The TIDS argument may be of the form
239 "file=<name>" in which case one or more TransportIDs can be read
240 from a file called <name>. See the "TRANSPORT IDs" section below
241 for more information.
242 -U, --unreg
244 optional when the PROUT register and move sub-command is
245 invoked. If given it will unregister the current initiator (I_T
246 nexus) after the other initiator has been registered and the
247 reservation moved to it. When not given the initiator (I_T
248 nexus) that sent the PROUT command remains registered.
249 -v, --verbose
251 print out cdb of issued commands prior to execution. If used
252 twice prints out the parameter block associated with the PROUT
253 command prior to its execution as well. If used thrice decodes
254 given transportID(s) as well. To see the response to a PRIN com‐
255 mand in low level form use the --hex option.
256 -V, --version
258 print out version string. Ignore all other parameters.
259 -? output usage message. Ignore all other parameters.
261
263 TransportIDs are used in persistent reservations to identify initia‐
264 tors. The format of a TransportID differs depending on the type of
265 transport being used. Their format is described in SPC-4 (in draft
266 revision 20 see section 7.5.4).
267 A TransportID is required for the PROUT 'register and move' sub-command
269 and the PROUT 'register' sub-command can have zero, one or more Trans‐
270 portIDs.
271 When the --transport-id=TIDS option is given then the TIDS argument may
273 be a comma (or single space) separated list of ASCII hex bytes that
274 represent a single TransportID as defined in SPC-4. Alternatively the
275 TIDS argument may be a transport specific string starting with either
276 "fcp,", "spi,", "sbp,", "srp,", "iqn", or "sas,". The "iqn" form is an
277 iSCSI qualified name. Apart from "iqn" the other transport specific
278 leadin string may be given in upper case (e.g. "FCP,").
279 The "fcp," form should be followed by 16 ASCII hex digits that repre‐
281 sent an initiator's N_PORT_NAME. The "spi," form should be followed by
282 "<scsi_address>,<relative_target_port_identifier>" (both decimal num‐
283 bers). The "sbp," form should be followed by 16 ASCII hex digits that
284 represent an initiator's EUI-64 name. The "srp," form should be fol‐
285 lowed by 32 ASCII hex digits that represent an initiator port identi‐
286 fier. The "sas," form should be followed by 16 ASCII hex digits that
287 represent an initiator's port SAS address.
288 There are two iSCSI qualified name forms. The shorter form contains the
290 iSCSI name of the initiator port (e.g. "iqn.5886.com.acme.diskar‐
291 rays-sn-a8675309"). The longer form adds the initiator session id (ISID
292 in hex) separated by ",i,0x". For example "iqn.5886.com.acme.diskar‐
293 rays-sn-a8675309,i,0x1234567890ab". On the command line to stop punc‐
294 tuation in an iSCSI name being (mis)-interpreted by the shell, putting
295 the option argument containing the iSCSI name in double quotes is
296 advised. iSCSI names are encoded in UTF-8 so if non (7 bit) ASCII char‐
297 acters appear in the iSCSI name on the command line, there will be dif‐
298 ficulties if they are not encoded in UTF-8. The locale can be changed
299 temporarily by prefixing the command line invocation of sg_persist with
300 "LANG=en_US.utf-8" for example.
301 Alternatively the TIDS argument may specify a file (or pipe) from which
303 one or more TransportIDs may be read. If the TIDS argument is "-" then
304 stdin (standard input) is read. If the TIDS argument is of the form
305 "file=<name>" than a file called <name> is read. A valid SPC-4 Trans‐
306 portID is built from the transport specific string outlined in the pre‐
307 vious paragraphs. The parsing of the data read is realtively simple.
308 Empty lines are ignored. Everything from and including a "#" on a line
309 is ignored. Leading spaces and tabs are ignored. There can be one
310 transportID per line. The transportID can either be a comma, space or
311 tab separated list of ASCII hex bytes that represent a TransportID as
312 defined in SPC-4. Padding with zero bytes to a minimum length of 24
313 bytes is performed if necessary. The transportID may also be transport
314 specific string type discussed above.
315 In SPC-3 the SPEC_I_PT bit set to one and TransportIDs were allowed for
317 the PROUT register and ignore existing key sub-command. In SPC-4 that
318 is disallowed yielding a CHECK CONDITION status with and ILLEGAL
319 REQUEST sense key and an additional sense code set to INVALID FIELD IN
320 PARAMETER LIST.
321
323 In the 2.4 series of Linux kernels the DEVICE must be a SCSI generic
324 (sg) device. In the 2.6 series any SCSI device name (e.g. /dev/sdc,
325 /dev/st1m or /dev/sg3) can be specified. For example "sg_persist
326 --read-keys /dev/sdb" will work in the 2.6 series kernels.
327 The only scope for PROUT commands supported in the current draft of
329 SPC-4 is "LU_SCOPE". Hence there seems to be no point in offering an
330 option to set scope to another value.
331 Most errors with the PROUT sub-commands (e.g. missing or mismatched
333 --prout-type=TYPE) will result in a RESERVATION CONFLICT status. This
334 can be a bit confusing when you know there is only one (active) initia‐
335 tor: the "conflict" is with the SPC standard, not another initiator.
336 Some recent disks accept some PRIN and PROUT sub-commands when the
338 media is stopped. One exception was setting the APTPL flag (with the
339 --param-aptpl option) during a key register operation, it complained if
340 the disk one stopped. The error indicated it wanted the disk spun up
341 and when that happened, the registration was successful.
342
344 These examples use Linux device names. For suitable device names in
345 other supported Operating Systems see the sg3_utils(8) man page.
346 Due to the various option defaults the simplest example executes the
348 'read keys' sub-command of the PRIN command:
349 sg_persist /dev/sdb
351 This is the same as the following (long-winded) command:
353 sg_persist --in --read-keys --device=/dev/sdb
355 To read the current reservation either the '--read-reservation' form or
357 the shorter '-r' can be used:
358 sg_persist -r /dev/sdb
360 To register the new reservation key 0x123abc the following could be
362 used:
363 sg_persist --out --register --param-sark=123abc /dev/sdb
365 Given the above registration succeeds, to reserve the DEVICE (with type
367 'write exclusive') the following could be used:
368 sg_persist --out --reserve --param-rk=123abc
370 --prout-type=1 /dev/sdb
371 To release the reservation the following can be given (note that the
373 --param-rk and --prout-type arguments must match those of the reserva‐
374 tion):
375 sg_persist --out --release --param-rk=123abc
377 --prout-type=1 /dev/sdb
378 Finally to unregister a reservation key (and not effect other registra‐
380 tions which is what '--clear' would do) the command is a little sur‐
381 prising:
382 sg_persist --out --register --param-rk=123abc /dev/sdb
384 Now have a close look at the difference between the register and unreg‐
386 ister examples above.
387 An example file that is suitably formatted to pass transportIDs via a
389 '--transport-id=file=transport_ids.txt' option can be found in the
390 examples sub-directory of the sg3_utils package. There is also a simple
391 test script called sg_persist_tst.sh in the same directory.
392 The above sequence of commands was tested successfully on a Seagate
394 Savvio 10K.3 disk which has a SAS interface.
395
397 The exit status of sg_persist is 0 when it is successful. Otherwise see
398 the sg3_utils(8) man page.
399
401 Written by Douglas Gilbert
402
404 Report bugs to <dgilbert at interlog dot com>.
405
407 Copyright © 2004-2012 Douglas Gilbert
408 This software is distributed under the GPL version 2. There is NO war‐
409 ranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR‐
410 POSE.
411
413 sg3_utils(sg3_utils), scsires(internet)
414sg3_utils-1.35 December 2012 SG_PERSIST(8)