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       amanda-devices - Configuring and Using Amanda Devices


       The Device API specifies a generic interface between Amanda and storage
       devices such as tapes or disks. This manual page describes the device
       drivers included with Amanda.

       This is a user-level description of the API, and does not address
       details that are only of concern to developers. For that purpose,
       consult the Amanda source code and

       The term "device driver" describes the software that can communicate
       with some kind of backend storage, e.g., a tape driver. A "device" is
       the storage element itself, usually a piece of hardware. When
       discussing a device and its driver as a unit, the term "device" is
       sometimes also used to refer to the combination of device and driver.


       Device names take the form TYPE:NODE, where TYPE selects a device
       driver, and NODE provides further information to that driver. The
       syntax for each device driver is given in the corresponding section

       Devices can be described in amanda.conf(5) with "device" sections,

       define device top_drive {
           tapedev "tape:/dev/nst0"
           device_property "BLOCK_SIZE" "131072"
       Such a device defininition creates a device "alias", in this case named
       top_drive, which can then be named in the global tapedev or tpchanger

       tapedev "top_drive"

       The global tapedev parameter can also specify a literal device name.
       For example,

       tapedev "file:/amdisks"
       is equivalent to

       tapedev "default"
       define device default {
           tapedev "file:/amdisks"
       Note that, in both cases, the specified devices are actually accessed
       through the chg-single changer driver; see amanda-changers(7) for more

       Device properties specified outside of any device definition apply to
       all devices. This syntax is provided mainly for backward compatibility,
       and for simple Amanda configurations. Note that there is no way to
       provide properties specific to a device without defining a device

       See amanda-changers(7) for details on how devices are configured, and
       in particular on how device properties are specified. See
       amanda.conf(5) for more information on Amanda configuration in general.

           There is no way to reset a device property to its default value.


       Device drivers use properties as a generic means to interact with other
       parts of Amanda. Some properties are set by the device driver and used
       by Amanda to determine how its devices should be used. Other properties
       can be set by Amanda or by the user to influence the driver´s behavior.
       Properties are set for a particular device, so that if you have two
       tape devices, they will not share property values.

       Properties are specified in amanda.conf with the device-property
       parameter. The syntax looks like this:

       device_property "FROBNICATOR_PATH" "/var/frobd/state"
       device_property "BYTES_PER_FORTNIGHT" "128k"
       device_property "USE_QUBITS" "no"

       Both the property name and the property value are always quoted.
       Property names, like Amanda configuration parameters, are not
       case-sensitive, and - (dash) and _ (underscore) may be used
       interchangeably. String values are given as simple strings, like
       FROBNICATOR_PATH in the example above. Integer values can be specified
       with any of the suffixes given in the "VALUE SUFFIXES" section of
       amanda.conf(5), like BYTES_PER_FORTNIGHT, above. Boolean values can be
       specified using the same names as in amanda.conf(5), like USE_QUBITS,
       above. Some properties have special formats, as described below.

       Some properties are set based on other configuration values, such as
       tapetype parameters. These special cases are detailed under the
       appropriate property, below.

       The order in which device properties are set is as follows:

        1. Tapetype parameters (including length, blocksize, and
           readblocksize) are translated into device properties and set

        2. Device properties from any device_property configuration parameters
           are set, in the order they appear in the configuration file.

       Properties described as read-only are not accessible to users. They are
       listed here for completeness.

       Note that some of these properties are currently unused, and present
       only for future expansion. Not all devices implement all of these


            (read-only) This boolean property indicates whether this device
           supports appending data to volumes.


            (read-write) This property gives the block size, in bytes, that
           will be used to write to the device.  The usual suffixes ("kbytes",
           etc.) are allowed.  The tapetype parameter blocksize sets this


            (read-only) This property contains the full canonical name for
           this device.  This name may not be the same as the user-supplied
           name, but is a valid name by which to access this device.


            (read-write) This string property is entirely for the user´s
           convenience.  It is supported by all devices, but no device
           interprets its value in any way.


            (read-write) This boolean property represents the compression
           status of the device, and can be used to enable and disable such
           compression.  This applies mostly to tape devices, although many
           tape devices do not support setting compression from software.


            (read-only) This property gives the compression rate, as a decimal
           ratio.  It may be a measured value over some unspecified period or
           a simple estimate.


            (read-only) This property indicates the level of concurrent access
           that this device supports.


            (read-only) This property gives the amount of free space available
           on the current volume, if known.  This is often an estimate; for
           example, tape devices can only estimate the amount of tape left on
           a spool.


            (read-only) This property indicates whether the device supports
           erasing the entire volume.  Aside from S3 and VFS, most devices
           cannot support this feature.


            (read-only) This property gives the maximum block size this device
           can support.  See BLOCK SIZES, below.


            (read-only) This property gives the type of the media in the
           device: read only, WORM (Write Once, Read Many), read/write, or
           write only.  Write-only devices do not support recovery, but the
           data are not necessarily thrown out.


            (read-write) This property gives the minimum block size this
           device can support.  See BLOCK SIZES, below.


            (read-write) On devices that support it, this property will limit
           the total amount of data written to a volume; attempts to write
           beyond this point will cause the device to simulate "out of space."
           Zero means no limit.  The tapetype parameter length sets this


            (read-only) This property indicates whether the device supports
           deletion of specific files.  Aside from linear tapes and S3, most
           devices can support this feature.  It is currently unused by


            (read-only) This property gives the streaming requirement for this
           device.  For example, tape drives often require a steady supply of
           data to avoid shoe-shining, while disk devices have no such


            (read-write) If this boolean property is set, then the device will
           produce verbose debugging output.  This property is not recognized
           by most devices.

       Amanda writes device data in blocks. On most devices the block
       boundaries are embedded in the media along with the data itself, so
       subsequent reads must use the same block sizes. On tape devices, the
       block size is dictated by the capabilities of the hardware -- buffer
       sizes, physical format, and so on.

       Amanda has historically supported a single, fixed block size -- usually
       32k. The Device API adds the ability to specify a block size at
       runtime, using the BLOCK_SIZE property. Devices provide MIN_BLOCK_SIZE
       and MAX_BLOCK_SIZE as a guide to the range of acceptable block sizes.
       Note that this does not imply that all sizes in the range
       MIN_BLOCK_SIZE - MAX_BLOCK_SIZE are available -- the device may require
       that block sizes are even multiples of some power of two, for example.
       Consult the documentation for your hardware and operating system for
       more information.

       Most devices are flexible enough to read a volume using a different
       block size than that with which it was written. This can be useful when
       handling old volumes written with a smaller blocksize, or volumes of
       unknown blocksize. Unfortunately, some tape devices do not detect
       oversized blocks correctly, and may lose data if the configured block
       size is smaller than the volume´s block size. The tape device driver
       has a READ_BLOCK_SIZE property which specifies the minimum buffer size
       that will be allocated for reads from tape. If the hardware supports
       it, setting this property allows Amanda to correctly read from tapes
       written with any blocksize less than or equal to READ_BLOCK_SIZE.

           The RAIT device does not support flexible block sizes, as its
           parity algorithm requires that all child devices have the same,
           fixed block size.


       This section lists the device drivers included with Amanda, and basic
       instructions for using them. For complete How-To information, consult
       the Amanda wiki at

   Null Device
       tapedev "null:"

       The null device driver only supports writing, and discards all data. It
       is generally only useful for testing purposes.

   RAIT Device
       tapedev "rait:tape:/dev/rmt/tps0d{4,5,6}n"

       The RAIT device driver mirrors or stripes data over multiple "child"
       devices. The child devices are specified using a shell-like syntax,
       where alternatives are enclosed in braces and separated by commas.
       Braces and commas can be escaped with a backslash. Note that the
       backslash itself must be escaped in most contexts. For example:

       tapedev "rait:{commandev:foo\\,bar,bracedev:foo\\}bar}"

       With two child devices, the RAIT device driver mirrors data such that
       the two devices contain identical data and can be used singly for
       recovery. With more than two devices, the RAIT device "stripes" data
       across all but one device and writes a parity block to the final
       device, usable for data recovery in the event of a device or volume
       failure. The RAIT device scales its blocksize as necessary to match the
       number of children that will be used to store data.

       When a child device is known to have failed, the RAIT device should be
       reconfigured to replace that device with the text "ERROR", e.g.,

       tapedev "rait:{tape:/dev/st0,ERROR,tape:/dev/st2}"
       This will cause the RAIT device to start up in degraded mode,
       reconstructing the data from the missing device.

       Like ordinary RAID drivers, the RAIT device driver can automatically
       enter degraded mode when one of its child devices fails. However, the
       RAIT device cannot automatically recover from any write error nor write
       any data in degraded mode. When reading, certain errors may be fatal
       (rather than causing degraded mode). And in any case, labels on all
       volumes must initially match (labeled or otherwise). If you have lost
       one volume from a set, explicitly start the device in degraded mode as
       described above.

   Child Device Block Sizes
       The RAIT device driver requires that all of its child devices use the
       same block size. If no block sizes are specified, the driver selects
       the block size closest to 32k that is within the MIN_BLOCK_SIZE -
       MAX_BLOCK_SIZE range of all child devices, and calculates its own
       blocksize according to the formula rait_blocksize = child_blocksize *
       (num_children - 1). If a block size is specified for the RAIT device,
       then it calculates its child block sizes according to the formula
       child_blocksize = rait_blocksize / (num_children - 1). Either way, it
       sets the BLOCK_SIZE property of each child device accordingly.

   S3 Device
       tapedev "s3:foocorp-backups/DailySet1-"
       device_property "S3_ACCESS_KEY" "MYACCESSKEY"
       device_property "S3_SECRET_KEY" "MYSECRETKEY"

       The S3 device driver uploads data to the Amazon S3 "storage cloud". Its
       device name is a slash-sparated combination of bucket name and prefix:
       "s3:BUCKET/PREFIX". Since buckets must be unique across all Amazon S3
       users, and since the number of buckets allowed to each user is limited,
       the driver can store multiple Amanda volumes in a single S3 bucket,
       distinguished by prefix. The prefix and slash can be omitted if they
       are not needed: "s3:BUCKET".

       The access and secret keys used to authenticate to Amazon S3 are
       provided as properties.

       The S3 device driver stores each block in a distinct S3 object. Due to
       high HTTP overhead for each request, use of larger than normal block
       sizes (> 1 megabyte) is reccomended with the S3 device.

       Amanda automatically creates a bucket when writing, if the bucket
       doesn´t already exist. At that time, it specifies where Amazon should
       store the data based on the S3_BUCKET_LOCATION property. Currently,
       there are two valid settings: "*" (any location, probably US) and "EU"
       (Europe). If this property is not set, Amazon´s default value of "*" is
       used. The bucket location has both billing and legal concerns, so you
       are encouraged to consult Amazon´s documentation for details.

       Amazon does not permit changes to bucket locations, so this is a
       permanent specification. If the bucket already exists and the property
       is set, then Amanda checks the property against the location of the
       bucket, and produces an error if they do not match.

           If a location constraint is set, the bucket name must consist only
           of lower-case letters, numbers, dashes, and dots.

       This driver supports the VERBOSE property, but use it carefully -- it
       produces a great deal of output, and may cause spurious failures by
       filling your debug log partition. Its logging is generally only useful
       for developers chasing down a problem in communications with Amazon´s

   Device-Specific Properties
       In addition to the common properties, the S3 device supports the
       properties listed in this section.

       Most Amanda devices work just fine without any properties, but not the
       S3 device. A typical S3 configuration will have an access key and
       secret key specified:

       device_property "S3_ACCESS_KEY" "27D3B8C6C4E7AA423C2B37C72A0D22C8"
       device_property "S3_SECRET_KEY" "agphc2Q7Zmxragphc2RmO2xragpzZGY7a2xqCgr"


           (read-write) Maximum speed, in bytes per second, that this device
           will receive data from S3.  If the average speed exceeds this
           value, the device will stop reading long enough to bring the
           average below this value.


           (read-write) Maximum speed, in bytes per second, that this device
           will send data to S3.  If the average speed exceeds this value, the
           device will stop writing long enough to bring the average below
           this value.


            (read-write) This property gives the Amazon S3 access key used to
           access the service.


            (read-write) Location constraint for buckets on Amazon S3.
           Currently, it can be set to "", for no constraint (i.e. store data
           in the US), or "EU" (i.e. store data in the EU).  See Amazon´s
           documentation for details and latest information


            (read-write) Path to CA certificate to use to verify the identity
           of the S3 server.  Only applicable when SSL/TLS is in use. The
           certificate should be in PEM format if OpenSSL or GnuTLS is being
           used with libcurl. Multiple certificates can be bundled together
           simply by concatenating them.  If NSS is being used, then it is the
           directory that the database resides in.  The value is passed to
           curl_easy_setopt(3) as CURLOPT_CAINFO.


            (read-write) This property gives the Amazon S3 secret key used to
           access the service.


            (read-write) Whether or not to use SSL/TLS to secure
           communications with Amazon S3.


            (read-write) This property specifies the user token for Amanda
           Enterprise Edition customers.


            (read-write) If true, verbose data about each HTTP transaction is
           sent to the debug log.

   Tape Device
       tapedev "tape:/dev/nst0"

       The tape device driver interacts with a tape drive. The device uses the
       operating system´s built-in tape support, which is generally similar to
       that available via the command-line utilities dd(1) and mt(1).

       The tape device name should specify a path to the operating system´s
       device file.

   Device-Specific Properties
       Most of these properties are automatically detected, but can be
       overridden in the configuration file if the autodetection fails. Note
       that tape drives are required to at least support the MTREW (rewind)
       operation; all other operations can be emulated with the MTREW and read
       data operations.


            (read-write) Set this boolean property if the system´s GMT_ONLINE
           macro gives incorrect results.  This is currently true for the
           Linux IDE-TAPE driver.


            (read-write) This boolean property specifies whether the device
            driver may execute the MTBSF operation (backward seek file).


            (read-write) This boolean property specifies whether the device
            driver should execute an MTBSF (backward seek file) operation
            MTEOM (seek to end of recorded data) in order to append.


            (read-write) This boolean property specifies whether the device
            driver may use the MTBSR operation (backward seek record).


            (read-write) This boolean property specifies whether the device
            driver may use the MTEOM command (seek to end of recorded data).


            (read-write) This integer property gives the number of filemarks
           that should be written at EOD.  It is usually 1 or 2.


            (read-write) This boolean property specifies whether the device
           driver may use the MTFSF operation (forward seek file).


            (read-write) This boolean property specifies whether the device
           driver needs a FSF to go the next file after the filemark is read.
           Default to "TRUE" on Solaris and "FALSE" on all others machines.


            (read-write) This boolean property specifies whether the device
           driver may use the MTFSR operation (forward seek record).


            (read-write) Set this boolean property to "true" if O_NONBLOCK
           must be used on the open call. Default to "true" on Linux and
           "false" on all others machines. Witout it, Linux wait for a few
           seconds if no tape are loaded. Solaris have strange error it is set
           to "yes".


            (read-write) This property (previously known as READ_BUFFER_SIZE)
           specifies the block size that will be used for reads; this should
           be large enough to contain any block that may be read from the
           device (for example, from a tape containing variable-sized blocks),
           and must be larger than BLOCK_SIZE.  This property is most often
           used when overwriting tapes using a new, smaller block size.
            The tapetype parameter READBLOCKSIZE sets this property.  See
           BLOCK SIZES, above.

   NDMP Device
       tapedev ""
       device_property "NDMP_USERNAME" "jimmy"
       device_property "NDMP_PASSWORD" "thelock"

       This device enables Amanda to communicate with a tape service on an
       NDMP server. The device name specifies the hostname and optionally the
       TCP port of the NDMP server, followed by the name of the tape device on
       the server (st1 in the example above).

   Device-Specific Properties
       The properties NDMP_USERNAME and NDMP_PASSWORD set the username and
       password with which to access the NDMP server. The default for both is


           (read-write) Authentication method to use to connect to the NDMP
           server.  One of "md5" (default), "text", "none" (for an empty
           authentication attempt) or "void" (for no authentication attempt at


           (read-write) Password for md5 or text authentications.


           (read-write) Username for md5 or text authentications.

   VFS Device
       tapedev "file:/path/to/vtape"

       The VFS device driver stores data on a UNIX filesystem. Note that
       although one typically uses the VFS device driver to store data on hard
       disks, the driver does not interface with any hardware on a block

       The device name specifies a path to a directory which must exist and
       contain a "data/" subdirectory. Each tape file is stored as a distinct
       file in this directory, the name of which reflects the Amanda header in
       the tape file. Block boundaries are not maintained: the driver supports
       reads of arbitrary size, regardless of the blocksize used to write the

   DVD-RW Device
       tapedev "dvdrw:/var/cache/amanda/dvd-cache:/dev/scd0"
       device_property "DVDRW_MOUNT_POINT" "/media/dvd"
       device_property "DVDRW_KEEP_CACHE" "false"
       device_property "DVDRW_UNLABELLED_WHEN_UNMOUNTABLE" "true"

       The DVD-RW device driver reads and writes optical media such as DVDs
       and CDs. The device name must specify a cache directory for data to be
       temporarily stored, followed by the operating system name for the
       optical drive. The cache directory must contain a "data/" subdirectory.

       The DVDRW_MOUNT_POINT property is required, and specifies a directory
       where the optical media can be mounted. This directory must be
       configured to enable non-root users to mount the optical media. On
       Linux, that means a line similar to the following in /etc/fstab:
       /dev/scd0 /media/dvd auto ro,user,noauto 0 0

       Note the "user" option.

       When writing data, the device acts as a VFS device using the given
       cache directory. On completion of writing the tape, the cache directory
       is written to optical media. The DVDRW_KEEP_CACHE property controls
       whether the cache contents are immediately deleted. When reading, the
       optical media is first mounted and read as a VFS device.

       Attempting to mount unformatted media or media that is formatted but
       contains no filesystem will usually result in an error. The boolean
       DVDRW_UNLABELLED_WHEN_UNMOUNTABLE property specifies whether media that
       cannot be mounted should be treated as an empty, unlabelled volume when
       attempting to read the volume label. It is necessary to set this
       property to "true" when labelling such media.

   Device-Specific Properties
       DVDRW_UMOUNT_COMMAND specify alternative commands for writing, mounting
       and unmounting optical media. The default is to find the programs using
       the PATH environment variable.

       The DVDRW_MOUNT_POINT property is required. Other properties are


            (read-write) Set this boolean property to "true" if the disk cache
           directory should be kept after successfully writing tape data to
           optical media. The default is false, which causes the cache
           contents to be deleted immediately after a successful write


            (read-write) This property specifies the filesystem mount point
           for the optical media. Non-root users must be able to mount optical
           media by invoking "mount" and specifying this mount point.


            (read-write) Treat unmountable media as empty, unlabelled media.
           This is necessary when attempting to label freshly formatted media.


            (read-write) The command to invoke to burn the DVD.


            (read-write) The command to invoke to mount the DVD.


            (read-write) The command to invoke to unmount the DVD.


       amanda(8), amanda.conf(5)

       The Amanda Wiki: :


       Ian Turner <>
           Zmanda, Inc. (

       Dustin J. Mitchell <>
           Zmanda, Inc. (