1AMANDA-CHANGERS(7) Miscellanea AMANDA-CHANGERS(7)
2
6 amanda-changers - Configuring and Using Amanda Changers
7
9 Amanda uses changers to arbitrate access to devices (amanda-devices(7))
10 and data volumes. Changers provide an abstraction of tape robots, but
11 are used to manage non-tape media, too. Amanda communicates with
12 changers through the Changer API. This manpage contains a user-level
13 overview of the API, and does not address details that are only of
14 concern to developers. For that purpose, consult the Amanda source code
15 and http://wiki.zmanda.com.
16
18 The Amanda Changer API version 1.0 is no longer supported.
19 The Amanda Changer API version 2.0, composed of perl objects that can
21 manage parallel access to multiple devices and other complexity. At
22 this point, all Amanda programs use the new Changer API directly.
23 The Changer API strives to treat all changers identically, so that
25 Amanda's behavior is independent of the changer in use. However, some
26 parts of Amanda operate differently depending on whether a changer can
27 efficiently search for a volume with a given label. This distinction is
28 really only apparent with tape libraries: those with barcode readers
29 can quickly find a desired tape, while those without may fall back to
30 an inefficient scan of each volume. The capability to perform quick
31 searches is called "fast-search", and each changer is annotated below
32 to indicate its support.
33
35 Changer specifications are strings like chg-disk:/my/vtapes. The chg-
36 prefix serves to differentiate changers from devices (see amanda-
37 devices(7)). The next portion (disk, in this case) identifies the
38 particular changer driver to use, and everything that follows the : is
39 interpreted by the driver. Note that the : character is required, even
40 when nothing follows it.
41 A name which does not match this pattern, is treated as an Amanda
43 device, and is wrapped by the single-device changer, e.g.,
44 chg-single:tape:/dev/rmt/0.
45 Changers which require additional parameters can also be described in
47 amanda.conf(5) with "changer" sections. Such a changer defininition
48 creates a changer "alias", in this case named hp-robot, which can then
49 be named where an application expects a changer - for example, the
50 target of the amvault command or in a global tpchanger parameter.
51 CONFIGURATION
53 The preferred method of specifying configuration for a changer is as a
54 "changer" section in amanda.conf(5). The tapedev parameter then
55 indicates, by name, the changer that will be used by default by most
56 Amanda programs. For example:
57 define changer hp-robot {
59 tapedev "chg-robot:/dev/sg1"
60 property "tape-device" "0=tape:/dev/nst0"
61 property append "tape-device" "1=tape:/dev/nst1"
62 device-property "BLOCK_SIZE" "512k"
63 }
64 # ...
65 tapedev "hp-robot"
66 Several changer drivers accept changer properties which control the
68 behavior of the changer. These properties must be specified in a
69 changer definition, as in the hp-robot example, above.
70 Devices, too, can take properties to control their behavior (see
72 amanda-devices(7)). Device properties can come from four places:
73 implicit device properties (from tapetype parameters), global device
74 properties (from global device-property parameters), properties in
75 device definitions, and properties in changer definitions. Properties
76 are applied in this order, with later properties taking priority.
77 There are only three implicit properties: MAX_VOLUME_USAGE is set based
79 on the tapetype length parameter, READ_BLOCK_SIZE is set if
80 readblocksize is set, and BLOCK_SIZE is set based on the blocksize
81 parameter.
82 Global device properties always apply. If the changer specifies a
84 device by alias, then device properties from the definition apply. If
85 the changer is specified by an alias, then properties from that
86 definition applied.
87
89 This section lists the changer drivers included with Amanda, and basic
90 instructions for using them. For complete How-To information, consult
91 the Amanda wiki at http://wiki.zmanda.com.
92 chg-aggregate:changer
94 define changer robot0 {
95 tpchanger "chg-robot:/dev/sg0"
96 property "tape-device" "0=tape:/dev/rmt/0" "1=tape:/dev/rmt/1"
97 }
98 define changer robot1 {
99 tpchanger "chg-robot:/dev/sg1"
100 property "tape-device" "0=tape:/dev/rmt/2" "1=tape:/dev/rmt/3"
101 }
102 define changer single {
103 tpchanger "chg-single:/dev/rmt/4"
104 }
105 define changer aggregate {
106 tpchanger "chg-aggregate:{robot0,robot1,single}"
107 property "state-filename" "/etc/amanda/CONF/aggregate.state"
108 }
110 tpchanger "aggregate"
111 This changer driver allow the use of two or more changers or standalone
113 drives in sequence.
114 Properties
116 LOCK-TIMEOUT
117 The time in seconds amanda wait to lock the statefile
119 (default:1000)
120 STATE_FILENAME
122 The name of the state file (default:
124 "$CONFIG_DIR/$changer_name.state".
125 chg-disk:VTAPEROOT
127 tpchanger "chg-disk:/var/mnt/vtapes"
128 property "num-slot" "10"
129 property "auto-create-slot" "yes"
130 property "removable" "yes"
131 property "mount" "yes"
132 property "umount" "yes"
133 property "umount-lockfile" "/etc/amanda/conf/vtapes-lock"
134 property "umount-idle" "1"
135 This changer driver replaces the old chg-disk, supporting parallel
137 access to vtapes stored in directories named slotN in the directory
138 specified after chg-disk:. It does so by creating numbered "drives" so
139 that simultaneous processes can access distinct slots. This changer is
140 fast-search capable.
141 The current slot can be accessed using the device name file:VTAPEROOT.
143 This is useful for the amrestore(8) command line.
144 Properties
146 AUTO-CREATE-SLOT
147 If a slotN directory in the range 1 to NUM-SLOT does not already
149 exist, and this property is true, then the changer will create the
150 directory.
151 LOCK-TIMEOUT
153 The time in seconds amanda wait to lock the statefile
155 (default:1000)
156 MOUNT
158 If this property is true, the changer try to mount the removable
160 disk if nothing is mounted. The system must be configured to allow
161 the amanda user to mount it.
162 NUM-SLOT
164 The minimum number of slots in the changer, where the first slot is
166 slot1. If additional slot directories exist, they will also be
167 used.
168 REMOVABLE
170 If this property is true, then the changer will verify that the
172 changer directory (e.g., /var/mnt/vtapes) is on a different
173 filesystem from its parent directory (e.g., /var/mnt). This is
174 useful for removable disks, as it will prevent Amanda from creating
175 slot directories when the removable disk is not mounted.
176 UMOUNT
178 If this property is true, the changer try to umount the removable
180 disk when it exit. The system must be configured to allow the
181 amanda user to umount it.
182 UMOUNT-LOCKFILE
184 If UMOUNT is set, it require a lockfile outside of the mount point
186 to prevent race.
187 UMOUNT-IDLE
189 If set, the changer try to umount the removable disk when it is not
191 in use. The umount-idle value is a delay in second to wait before
192 doing the umount. A value >= 1 is required to prevent useless
193 mount/umount.
194 chg-multi:DEVICE-LIST
196 tpchanger "chg-multi:{/dev/nst0,/dev/nst1,/dev/nst2}"
197 changerfile "chg-multi-state"
198 This script simply round-robins a number of distinct device names, as
200 specified in the tpchanger setting. It is useful when all volumes for a
201 configuration have different device names -- for example, if you have
202 many standalone drive. The changerfile must exist; it is used to save
203 the state file.
204 The child devices are specified using the same syntax as for the RAIT
206 device (see amanda-changers(7)). The range specification can be
207 especially useful here:
208 tpchanger "chg-multi:s3:mycompany-backups/tape-{001..100}"
210 This changer is not fast-search capable.
212 Properties
214 FIRST-SLOT
215 This property gives the number of the first slot. The default value
217 is "1".
218 LOCK-TIMEOUT
220 The time in seconds amanda wait to lock the statefile
222 (default:1000)
223 Special Operations
225 A number of special operations are available for chg-multi via
226 amtape(8) subcommands.
227 The reset subcommand will change the current slot to the first
229 available slot, but does not erase any stored state maintained by the
230 changer.
231 The eject subcommand will eject the volume in the given drive
233 The clean subcommand is not yet implemented.
235 The update subcommand instructs the changer to update its state
237 database. Given no arguments, the changer will scan all available
238 slots, loading each tape and reading its label. Especially for large
239 libraries, this can take a long time. If only a few slots have changed,
240 they can be listed on the command line:
241 amtape CONFIG update 1-3,9
243 In this case, the changer will only scan the stated slots. Finally, the
244 changer will not scan at all if it is given the tape label for the
245 slot:
246 amtape CONFIG update 2=DailySet-028
248 In this case, the changer updates its state to indicate that
249 DailySet-028 is in slot 2, without trying to load the tape.
250 amtape CONFIG update 1-3,9=
252 In this case, the changer marks the stated slots as an unknown state.
253 amtape CONFIG update error=
255 In this case, the changer marks all slot in error as an unknown state.
256 chg-rait:{CHILD1,CHILD2,..}
258 define changer vtape {
259 tpchanger "chg-disk:/path/to/vtape"
260 }
261 define changer robot {
262 tpchanger "chg-robot:/dev/sg0"
263 tapedev "tape:/dev/nst0"
264 }
265 tpchanger "chg-rait:{vtape,robot}"
266 This changer script constructs RAIT devices out of the devices provided
268 by several "sub-changers". The sub-changers are specified using the
269 same shell-like syntax as the RAIT device (see amanda-devices(7)).
270 Chg-rait does not require that all of the child changers have the same
272 slot names: compound slot names are created by combining the slot names
273 supplied by the child changers using the same shell-like syntax. For
274 example, if the child changers return slots "top", "strange", and "3",
275 then the RAIT changer will return "{top,strange,3}". This makes it
276 possible to, for example, mirror data on tapes in slots 1-10 to tapes
277 in slots 11-20 of the same robot, using two chg-zd-mtx child changers
278 (and, naturally, two tape drives). In this arrangement, the first slot
279 would be named {1,11}.
280 As a convenience to the user, the RAIT changer will also accept
282 un-braced slot names, and supply the same name to each child changer.
283 Thus with a 4-device RAIT changer, "17" is equivalent to
284 "{17,17,17,17}".
285 Drive names are parsed in a similar fashion, for operations that take
287 drive names (clean and eject).
288 This changer is fast-search capable only if all of its child changers
290 are fast-search capable.
291 chg-null:
293 tpchanger "chg-null:"
294 This changer always provides the device "null:". It is sometimes useful
296 in conjunction with chg-rait:.
297 chg-robot:DEVICE
299 define changer robot {
300 tpchanger "chg-robot:/dev/sg0"
301 property "tape-device" "0=tape:/dev/rmt/0" "1=tape:/dev/rmt/1"
302 property "eject-before-unload" "yes"
303 property "use-slots" "1-5,11-20"
304 }
305 tpchanger "robot"
306 This changer drives a robotic tape library using the operating system's
308 mtx command. It replaces the ancient chg-zd-mtx script. The changer
309 uses all of the information available to operate as efficiently as
310 possible. Even without a barcode reader, the changer can usually load a
311 tape immediately, without resorting to a sequential scan of many tapes.
312 It is capable of sharing state across multiple Amanda configurations,
313 avoiding conflicts and optimally tracking the contents of the library.
314 This changer does not accept a changerdev parameter, but the
316 changerfile parameter can be used to specify a filename at which it
317 should store its state. Ordinarily, this state is stored in a file
318 named after the changer device under $localstatedir/amanda, e.g.,
319 /var/amanda/chg-robot-dev-sg0. There should be a single such statefile
320 for each distinct tape library attached to the Amanda server, even if
321 multiple Amanda configurations reference that library.
322 With a barcode reader present, it is possible for chg-robot to track
324 the state of the library reliably, even recognizing tapes that are
325 removed and later re-inserted (by remembering their barcodes). Without
326 barcodes, the changer can still remember the slot in which it last saw
327 the tape with a particular label, although this information can become
328 stale if the tapes are rearranged by an operator. In any case, the
329 changer will never "hunt" for a tape by repeatedly loading slots and
330 checking labels. If the changer's state is inaccurate, use the
331 amtape(8) subcommand update.
332 This changer is fast-search capable even without a barcode reader. For
334 such libraries, it is the responsibility of the operator to update the
335 changer when tapes are added to or removed from the library.
336 There is a shell script in the contrib/ directory of Amanda's source
338 distribution which can help you convert a chg-zd-mtx configuration into
339 a chg-robot configuration. Just give it your Amanda configuration name:
340 sh contrib/convert-zd-mtx-to-robot.sh $config
342 The script can be downloaded at
343 http://github.com/zmanda/amanda/raw/master/contrib/convert-zd-mtx-to-robot.sh
344 Special Operations
346 A number of special operations are available for chg-robot via
347 amtape(8) subcommands.
348 The reset subcommand will change the current slot to the first
350 available slot, but does not erase any stored state maintained by the
351 changer.
352 The eject subcommand will unload the volume in the given drive,
354 ejecting first if the changer properties dictate. Note that, despite
355 the subcommand name, the changer attempts to avoid the state where a
356 volume has been ejected from the drive but not unloaded back to a
357 storage slot.
358 The clean subcommand is not yet implemented.
360 The update subcommand instructs the changer to update its state
362 database. Given no arguments, the changer will scan all available
363 slots, loading each tape and reading its label. Especially for large
364 libraries, this can take a long time. If only a few slots have changed,
365 they can be listed on the command line:
366 amtape CONFIG update 1-3,9
368 In this case, the changer will only scan the stated slots. Finally, the
369 changer will not scan at all if it is given the tape label for the
370 slot:
371 amtape CONFIG update 2=DailySet-028
373 In this case, the changer updates its state to indicate that
374 DailySet-028 is in slot 2, without trying to load the tape.
375 amtape CONFIG update 1-3,9=
377 In this case, the changer marks the stated slots as an unknown state.
378 amtape CONFIG update error=
380 In this case, the changer marks all slot in error as an unknown state.
381 Properties
383 BROKEN-DRIVE-LOADED-SLOT
384 Set this boolean property to true if mtx doesn't return correctly
386 which slot is loaded in a drive.
387 DRIVE-CHOICE
389 This property controls the algorithm used to select a drive in
391 which to load a tape. If set to the default ("lru"), the changer
392 attempts to use the least recently used drive, resulting in a
393 round-robin behavior. The "firstavail" algorithm selects the first
394 available drive, thus preferring the first drive specified via the
395 TAPE-DEVICE property.
396 EJECT-BEFORE-UNLOAD
398 Set this boolean property to true if the library requires an
400 offline operation be performed on the tape drive before it can be
401 unloaded. If set, then mt will be invoked to perform this
402 operation. Most libraries do not require this workaround.
403 EJECT-DELAY
405 This is the time between ejecting a tape and unloading the volume
407 to a storage slot, and defaults to 0 seconds. It is only used if
408 EJECT-BEFORE-UNLOAD is true. See "Timing", below.
409 FAST-SEARCH
411 This boolean property indicates whether the changer advertises the
413 ability to find volumes without sequential scanning. The
414 traditional taperscan algorithm alters its behavior based on this
415 flag, so it is sometimes necessary to adjust it, although the
416 changer will always search for a desired tape using the most
417 efficient means available. The default value is true.
418 IGNORE-BARCODES
420 If this boolean property is true, then chg-robot will ignore any
422 barcode information that the library provides. This property is
423 probably only useful when the library returns incorrect barcodes,
424 for example due to a malfunction in the barcode reader.
425 LOAD-POLL
427 This property specifies the timing of Amanda's polling for the tape
428 drive to be ready after loading a new tape. See "Timing", below.
429 The script "polls" by trying to open the tape device repeatedly
431 until no error is encountered. The property specifies the time to
432 wait before the first poll (D), the frequency at which to poll and
433 retry on errors (P); and the time after which it should give up
434 (U). The format is
435 "D [poll P [until U]]"
437 For a simple delay with no polling, use e.g.,
438 property "load-poll" "13s"
440 To delay and then poll, use e.g.,
441 property "load-poll" "13s poll 5s"
443 and to add a maximum total time, use e.g.,
444 property "load-poll" "0s poll 5s until 2m"
446 The default value is "0s poll 3s until 2m".
447 LOCK-TIMEOUT
449 The time in seconds amanda wait to lock the statefile
451 (default:1000)
452 MTX
454 The path to the 'mtx' binary. The default value is defined at
456 compile time.
457 STATUS-INTERVAL
459 This is the minimum time between invocations of mtx status to
461 determine the state of the changer library. The default value, 2
462 seconds, avoids back-to-back status invocations but ensures that
463 the metadata is up to date. For operating systems or libraries
464 where the mtx status takes a considerable time to complete, this
465 value should be increased. See "Timing", below.
466 TAPE-DEVICE
468 This property describes the correspondence of drive numbers in the
470 library to Amanda devices, in the format DRIVE=DEVICE. The
471 property can be specified multiple times to describe multiple
472 devices. The device will usually be a tape device name starting
473 with tape:, but may also refer to a device alias (see amanda-
474 devices(7)). As a shortcut, if the tapedev parameter is specified
475 in the changer definition, then it is assumed to be the device name
476 for drive 0.
477 UNLOAD-DELAY
479 This specifies the minimum time between an unload operation any any
481 subsequent operation. The default value is 0 seconds. See
482 "Timing", below.
483 USE-SLOTS
485 This property, if specifies, enumerates the slots to which this
487 changer should limit itself. The slots are specified as a
488 comma-separated list of ranges, e.g., "1-5,11-15,19,22". The
489 property can be specified more than once, and the resulting sets
490 will be combined. The changer will refuse to load tapes not found
491 in these slots, except for import/export purposes.
492 Timing
494 Tape libraries are fickle, and in many cases will report that an
495 operation is complete when it is still in progress. Chg-robot takes
496 several timing-related properties to accommodate such behavior.
497 A typical sequence of operations performed during a load are: get
499 library status, eject a tape, unload the tape back to a storage slot,
500 load a new tape, and read the label on that tape to ensure the drive is
501 ready.
502 On most systems, the library status check is nearly instantaneous --
504 the changer library provides its cached state to the host without
505 initiating any robot motion. In order to keep its metadata up-to-date,
506 chg-robot runs this command very frequently, but this frequency can be
507 reduced (at the cost of potentially stale metadata) by setting the
508 STATUS-INTERVAL property to a larger value.
509 Some tape libraries do not integrate the eject operation (performed by
511 the embedded tape drive) with the unload operation (performed by the
512 library robot), and can actually cause physical damage by attempting to
513 remove the tape before the ejection is complete. For such changers, set
514 the EJECT-DELAY property to allow enough time for the eject to
515 complete.
516 Once a tape is unloaded, if the library needs time to "quiesce" before
518 processing another command, add that time to the UNLOAD-DELAY
519 parameter. No other operations will be performed on the library until
520 this delay has elapsed.
521 Once a tape has been loaded, chg-robot waits until the drive is ready
523 before allowing Amanda to use the volume, as described for LOAD-POLL,
524 above.
525 Each of the times specified in these properties may be given as
527 integers with the optional suffix s for seconds (the default) or m for
528 minutes.
529 chg-ndmp:HOST[:PORT]@SCSIDEV
531 tpchanger "chg-ndmp:filer.company.com@/dev/sg0"
532 property "tape-device" "0=ndmp:filer.company.com@/dev/rtape0"
533 property append "tape-device" "1=ndmp:filer.company.com@/dev/rtape1"
534 property "use-slots" "1-12"
535 property "ndmp-auth" "text"
536 property "ndmp-username" "luke"
537 property "ndmp-password" "leia"
538 This changer is very similar to chg-robot, but controls a tape changer
540 on an NDMP server instead of a local device. The HOST in the tpchanger
541 should be the hostname of the NDMP server. The PORT is optional. The
542 SCSIDEV should specify the SCSI device on the NDMP server which
543 controls the changer. The format of this parameter is
544 implementation-specific.
545 The appropriate authentication properties will be automatically set on
547 any devices created by this changer.
548 Properties
550 This changer supports all of the properties supported by chg-robot,
551 although the value of MTX is ignored. The following properties are also
552 recognized:
553 NDMP_AUTH
555 Authentication method to use to connect to the NDMP server. One of
557 "md5" (default), "text", "none" (for an empty authentication
558 attempt) or "void" (for no authentication attempt at all).
559 NDMP-PASSWORD
561 The password for the NDMP server.
563 NDMP-USERNAME
565 The username for the NDMP server.
567 VERBOSE
569 If true, enables the NDMJOB library's verbose (packet-level)
571 debugging.
572 chg-single:DEVICE
574 tpchanger "chg-single:tape:/dev/nst0"
575 This changer is for use with standalone drive, it can work with any
577 device. The device (tape:/dev/nst0) must be set in the tpchanger
578 definition.
579 The chg-single changer has no property.
581 Unmaintained Changers
583 Amanda has many other changer scripts and programs beyond those
584 described here (see the changer-src/ in the source directory), but most
585 of these scripts are unmaintained and undocumented, and will be removed
586 when the new changer API is fully implemented.
587
589 amanda(8), amanda.conf(5), amanda-devices(7)
590 The Amanda Wiki: : http://wiki.zmanda.com/
592
594 Dustin J. Mitchell <dustin@zmanda.com>
595 Zmanda, Inc. (http://www.zmanda.com)
596Amanda 3.5.1 12/01/2017 AMANDA-CHANGERS(7)