AMANDA-CHANGERS(7) Miscellanea AMANDA-CHANGERS(7)NAMEamanda-changers - Configuring and Using Amanda Changers
DESCRIPTION
Amanda uses changers to arbitrate access to devices (amanda-devices(7))
and data volumes. Changers provide an abstraction of tape robots, but
are used to manage non-tape media, too. Amanda communicates with
changers through the Changer API. This manpage contains a user-level
overview of the API, and does not address details that are only of
concern to developers. For that purpose, consult the Amanda source code
and http://wiki.zmanda.com.
TRANSITION
The Amanda Changer API is in transition from version 1.0 - driven by
shell scripts invoked for each changer operation - to version 2.0,
composed of perl objects that can manage parallel access to multiple
devices and other complexity. When this transition is complete, Amanda
devices will, in general, be specified via a changer, which will
provide the necessary device specifier to access a requested volume. In
the interim, support for the "new" changer syntax is limited to the
experimental amvault(8).
SPECIFYING CHANGERS
Changer specifications are strings like chg-disk:/my/vtapes. The chg-
prefix serves to differentiate changers from devices (see amanda-
devices(7)). The next portion (disk, in this case) identifies the
particular changer driver to use, and everything that follows the : is
interpreted by the driver.
A name which does not match this pattern, but which matches an old
changer script (e.g., chg-zd-mtx), invokes the backward-compatibility
changer driver as chg-compat:chg-zd-mtx. If the name does not match an
old changer, then it is treated as an Amanda device, and is wrapped by
the single-device changer, e.g., chg-single:tape:/dev/rmt/0.
Changers which require additional parameters can also be described in
amanda.conf(5) with "changer" sections, for example,
define changer hp-robot {
tapedev "chg-robot:/dev/sg1"
property "drives" "0=/dev/nst0;1=/dev/nst0"
property "slots" "1-10"
}
(note that "chg-robot" is not yet implemented, so this is
hypothetical). A changer defininition creates a changer "alias", in
this case named hp-robot, which can then be named where an application
expects a changer - for example, the target of the amvault command.
CHANGER DRIVERS
This section lists the changer drivers included with Amanda, and basic
instructions for using them. For complete How-To information, consult
the Amanda wiki at http://wiki.zmanda.com.
chg-disk (new)
tpchanger "chg-disk:/u01/vtapes"
This changer driver replaces the old chg-disk, supporting parallel
access to vtapes stored in directories named slotN in the directory
specified after chg-disk:. It does so by creating numbered "drives" so
that simultaneous processes can access distinct slots.
chg-disk (old)
tapedev "file:/u01/vtapes"
tpchanger "chg-disk"
This changer script supports sequential access to vtapes stored in
directories named slotN in the directory specified by the tapedev
parameter.
chg-multi
tpchanger "chg-multi"
changerfile "chg-multi-state"
This script simply round-robins a number of distinct device names, as
specified in its configuration file. It is useful when all volumes for
a configuration have different device names -- for example, with S3
devices. The changerfile need not exist; it is used as a prefix for
filenames of state files.
chg-manual
tpchanger "chg-manual"
changerfile "chg-manual.conf"
This script simply provides distinct device names in a round-robin
fashion, as specified in its configuration file. It is useful when all
volumes for a configuration have different device names -- for example,
with S3 devices. The configuration file parameters are (as listed in
the script):
resend_mail=900 # resend mail every __ seconds
timeout_mail=604800 # time out after this many seconds (default 7 days)
request="[type]" # How to request a new tape (default "tty_email")
request="tty" # Use the tty to ask the user to change tape.
# Can´t be use by cron
request="email" # Send an email to ask the user to change tape.
request="tty_email" # Use the tty if it exist or send an email.
chg-zd-mtx
tpchanger "chg-zd-mtx"
changerdev "/dev/sg0" # used with ´mtx -f´
changerfile "chg-zd-mtx.conf"
tapedev "tape:/dev/nst0"
This script interfaces with a tape drive using the Zubkoff/Dandelion
version of mtx. That´s the version that takes a device specifier with
the -f option and has subcommands like status. The configuration file
parameters are (as listed in the script itself):
firstslot=? #### First storage slot (element)
lastslot=? #### Last storage slot (element)
cleanslot=-1 #### Slot with cleaner tape -- default is "-1"
#### Set negative to indicate no cleaner available
driveslot=0 #### Drive slot number. Defaults to 0
#### Use the ´Data Transfer Element´ you want
autoclean=0 #### Set to ´1´ or greater to enable
autocleancount=99 #### Number of access before a clean.
havereader=0 #### If you have a barcode reader, set to 1.
offline_before_unload=0 #### Does your robot require an
#### ´mt offline´ before mtx unload?
poll_drive_ready=NN #### Time (seconds) between tests to see if
#### the tape drive has gone ready (default: 3).
max_drive_wait=NN #### Maximum time (seconds) to wait for the
#### tape drive to become ready (default: 120).
initial_poll_delay=NN #### initial delay after load before polling for
#### readiness
slotinfofile=FILENAME #### record slot information to this file, in
#### the line-based format "SLOT LABEL\n"
chg-rait
tpchanger "chg-rait"
changerfile "chg-rait.conf"
This changer script constructs RAIT devices out of the devices provided
by several "sub-changers". The configuration file specifies nchangers,
the number of subchangers, and then provides tpchanger, changerdev_N,
changerfile_N, and tpchanger_N for each sub-changer, 1 through N.
chg-null
tpchanger "chg-null"
This changer always provides the device "null:". It is sometimes useful
in conjunction with chg-rait.
Unmaintained Changers
Amanda has many other changer scripts and programs beyond those
described here (see the changer-src/ in the source directory), but most
of these scripts are unmaintained and undocumented, and will be removed
when the new changer API is fully implemented.
SEE ALSOamanda(8), amanda.conf(5), amanda-devices(7),
AUTHOR
Dustin J. Mitchell <dustin@zmanda.com>
Zmanda, Inc. (http://www.zmanda.com)
Amanda 2.6.1p2 11/05/2009 AMANDA-CHANGERS(7)
