Subsections

Storage Daemon Configuration

The Storage Daemon configuration file has relatively few resource definitions. However, due to the great variation in backup media and system capabilities, the storage daemon must be highly configurable. As a consequence, there are quite a large number of directives in the Device Resource definition that allow you to define all the characteristics of your Storage device (normally a tape drive). Fortunately, with modern storage devices, the defaults are sufficient, and very few directives are actually needed.

Examples of Device resource directives that are known to work for a number of common tape drives can be found in the <bacula-src>/examples/devices directory, and most will also be listed here.

For a general discussion of configuration file and resources including the data types recognized by Bacula, please see the Configuration chapter of this manual. The following Storage Resource definitions must be defined:

Storage -- to define the name of the Storage daemon.
Director -- to define the Director's name and his access password.
Device -- to define the characteristics of your storage device (tape drive).
Messages -- to define where error and information messages are to be sent.

Storage Resource

In general, the properties specified under the Storage resource define global properties of the Storage daemon. Each Storage daemon configuration file must have one and only one Storage resource definition.

Name = <Storage-Daemon-Name>

Specifies the Name of the Storage daemon. This directive is required.

Working Directory = <Directory>

This directive is mandatory and specifies a directory in which the Storage daemon may put its status files. This directory should be used only by Bacula, but may be shared by other Bacula daemons provided the names given to each daemon are unique. This directive is required

Pid Directory = <Directory>

This directive is mandatory and specifies a directory in which the Director may put its process Id file files. The process Id file is used to shutdown Bacula and to prevent multiple copies of Bacula from running simultaneously. This directive is required. Standard shell expansion of the Directory is done when the configuration file is read so that values such as $HOME will be properly expanded.

Typically on Linux systems, you will set this to: /var/run. If you are not installing Bacula in the system directories, you can use the Working Directory as defined above.

Heartbeat Interval = <time-interval>

This directive defines an interval of time in seconds. When the Storage daemon is waiting for the operator to mount a tape, each time interval, it will send a heartbeat signal to the File daemon. The default interval is zero which disables the heartbeat. This feature is particularly useful if you have a router such as 3Com that does not follow Internet standards and times out an valid connection after a short duration despite the fact that keepalive is set. This usually results in a broken pipe error message.

Client Connect Wait = <time-interval>

This directive defines an interval of time in seconds that the Storage daemon will wait for a Client (the File daemon) to connect. The default is 30 seconds. Be aware that the longer the Storage daemon waits for a Client, the more resources will be tied up.

Maximum Concurrent Jobs = <number>

where <number> is the maximum number of Jobs that should run concurrently. The default is set to 10, but you may set it to a larger number. Each contact from the Director (e.g. status request, job start request) is considered as a Job, so if you want to be able to do a status request in the console at the same time as a Job is running, you will need to set this value greater than 1. To run simultaneous Jobs, you will need to set a number of other directives in the Director's configuration file. Which ones you set depend on what you want, but you will almost certainly need to set the Maximum Concurrent Jobs in the Storage resource in the Director's configuration file and possibly those in the Job and Client resources.

SDAddresses = <IP-address-specification>

Specify the ports and addresses on which the Storage daemon will listen for Director connections. Normally, the default is sufficient and you do not need to specify this directive. Probably the simplest way to explain how this directive works is to show an example:

 SDAddresses  = { ip = {
        addr = 1.2.3.4; port = 1205; }
    ipv4 = {
        addr = 1.2.3.4; port = http; }
    ipv6 = {
        addr = 1.2.3.4;
        port = 1205;
    }
    ip = {
        addr = 1.2.3.4
        port = 1205
    }
    ip = {
        addr = 1.2.3.4
    }
    ip = {
        addr = 201:220:222::2
    }
    ip = {
        addr = bluedot.thun.net
    }
}

where ip, ip4, ip6, addr, and port are all keywords. Note, that the address can be specified as either a dotted quadruple, or IPv6 colon notation, or as a symbolic name (only in the ip specification). Also, port can be specified as a number or as the mnemonic value from the /etc/services file. If a port is not specified, the default will be used. If an ip section is specified, the resolution can be made either by IPv4 or IPv6. If ip4 is specified, then only IPv4 resolutions will be permitted, and likewise with ip6.

Using this directive, you can replace both the SDPort and SDAddress directives shown below.

SDPort = <port-number>

Specifies port number on which the Storage daemon listens for Director connections. The default is 9103.

SDAddress = <IP-Address>

This directive is optional, and if it is specified, it will cause the Storage daemon server (for Director and File daemon connections) to bind to the specified IP-Address, which is either a domain name or an IP address specified as a dotted quadruple. If this directive is not specified, the Storage daemon will bind to any available address (the default).

The following is a typical Storage daemon Storage definition.

#
# "Global" Storage daemon configuration specifications appear
# under the Storage resource.
#
Storage {
  Name = "Storage daemon"
  Address = localhost
  WorkingDirectory = "~/bacula/working"
  Pid    Directory = "~/bacula/working"
}

Director Resource

The Director resource specifies the Name of the Director which is permitted to use the services of the Storage daemon. There may be multiple Director resources. The Director Name and Password must match the corresponding values in the Director's configuration file.

Name = <Director-Name>

Specifies the Name of the Director allowed to connect to the Storage daemon. This directive is required.

Password = <Director-password>

Specifies the password that must be supplied by the above named Director. This directive is required.

Monitor = <yes|no>

If Monitor is set to no (default), this director will have full access to this Storage daemon. If Monitor is set to yes, this director will only be able to fetch the current status of this Storage daemon.

Please note that if this director is being used by a Monitor, we highly recommend to set this directive to yes to avoid serious security problems.

The following is an example of a valid Director resource definition:

Director {
  Name = MainDirector
  Password = my_secret_password
}

Device Resource

The Device Resource specifies the details of each device (normally a tape drive) that can be used by the Storage daemon. There may be multiple Device resources for a single Storage daemon. In general, the properties specified within the Device resource are specific to the Device.

Name = Device-Name

Specifies the Name that the Director will use when asking to backup or restore to or from to this device. This is the logical Device name, and may be any string up to 127 characters in length. It is generally a good idea to make it correspond to the English name of the backup device. The physical name of the device is specified on the Archive Device directive described below. The name you specify here is also used in your Director's conf file on the Device directive in its Storage resource.

Archive Device = name-string

The specified name-string gives the system file name of the storage device managed by this storage daemon. This will usually be the device file name of a removable storage device (tape drive), for example " /dev/nst0" or "/dev/rmt/0mbn". For a DVD-writer, it will be for example /dev/hdc. It may also be a directory name if you are archiving to disk storage. In this case, you must supply the full absolute path to the directory. When specifying a tape device, it is preferable that the "non-rewind" variant of the device file name be given. In addition, on systems such as Sun, which have multiple tape access methods, you must be sure to specify to use Berkeley I/O conventions with the device. The b in the Solaris (Sun) archive specification /dev/rmt/0mbn is what is needed in this case. Bacula does not support SysV tape drive behavior.

As noted above, normally the Archive Device is the name of a tape drive, but you may also specify an absolute path to an existing directory. If the Device is a directory Bacula will write to file storage in the specified directory, and the filename used will be the Volume name as specified in the Catalog. If you want to write into more than one directory (i.e. to spread the load to different disk drives), you will need to define two Device resources, each containing an Archive Device with a different directory. In addition to a tape device name or a directory name, Bacula will accept the name of a FIFO. A FIFO is a special kind of file that connects two programs via kernel memory. If a FIFO device is specified for a backup operation, you must have a program that reads what Bacula writes into the FIFO. When the Storage daemon starts the job, it will wait for MaximumOpenWait seconds for the read program to start reading, and then time it out and terminate the job. As a consequence, it is best to start the read program at the beginning of the job perhaps with the RunBeforeJob directive. For this kind of device, you never want to specify AlwaysOpen, because you want the Storage daemon to open it only when a job starts, so you must explicitly set it to No. Since a FIFO is a one way device, Bacula will not attempt to read a label of a FIFO device, but will simply write on it. To create a FIFO Volume in the catalog, use the add command rather than the label command to avoid attempting to write a label.

Device {
  Name = FifoStorage
  Media Type = Fifo
  Device Type = Fifo
  Archive Device = /tmp/fifo
  LabelMedia = yes
  Random Access = no
  AutomaticMount = no
  RemovableMedia = no
  MaximumOpenWait = 60
  AlwaysOpen = no
}

During a restore operation, if the Archive Device is a FIFO, Bacula will attempt to read from the FIFO, so you must have an external program that writes into the FIFO. Bacula will wait MaximumOpenWait seconds for the program to begin writing and will then time it out and terminate the job. As noted above, you may use the RunBeforeJob to start the writer program at the beginning of the job.

The Archive Device directive is required.

Device Type = type-specification

The Device Type specification allows you to explicitly tell Bacula what kind of device you are defining. It the type-specification may be one of the following:

File: Tells Bacula that the device is a file. It may either be a file defined on fixed medium or a removable filesystem such as USB. All files must be random access devices.
Tape: The device is a tape device and thus is sequential access. Tape devices are controlled using ioctl() calls.
Fifo: The device is a first-in-first out sequential access read-only or write-only device.
DVD: The device is a DVD. DVDs are sequential access for writing, but random access for reading.

The Device Type directive is not required, and if not specified, Bacula will attempt to guess what kind of device has been specified using the Archive Device specification supplied. There are several advantages to explicitly specifying the Device Type. First, on some systems, block and character devices have the same type, which means that on those systems, Bacula is unlikely to be able to correctly guess that a device is a DVD. Secondly, if you explicitly specify the Device Type, the mount point need not be defined until the device is opened. This is the case with most removable devices such as USB that are mounted by the HAL daemon. If the Device Type is not explicitly specified, then the mount point must exist when the Storage daemon starts.

This directive was implemented in Bacula version 1.38.6.

Media Type = name-string

The specified name-string names the type of media supported by this device, for example, "DLT7000". Media type names are arbitrary in that you set them to anything you want, but they must be known to the volume database to keep track of which storage daemons can read which volumes. In general, each different storage type should have a unique Media Type associated with it. The same name-string must appear in the appropriate Storage resource definition in the Director's configuration file.

Even though the names you assign are arbitrary (i.e. you choose the name you want), you should take care in specifying them because the Media Type is used to determine which storage device Bacula will select during restore. Thus you should probably use the same Media Type specification for all drives where the Media can be freely interchanged. This is not generally an issue if you have a single Storage daemon, but it is with multiple Storage daemons, especially if they have incompatible media.

For example, if you specify a Media Type of "DDS-4" then during the restore, Bacula will be able to choose any Storage Daemon that handles "DDS-4". If you have an autochanger, you might want to name the Media Type in a way that is unique to the autochanger, unless you wish to possibly use the Volumes in other drives. You should also ensure to have unique Media Type names if the Media is not compatible between drives. This specification is required for all devices.

In addition, if you are using disk storage, each Device resource will generally have a different mount point or directory. In order for Bacula to select the correct Device resource, each one must have a unique Media Type.

Autochanger = Yes|No

If Yes, this device belongs to an automatic tape changer, and you must specify an Autochanger resource that points to the Device resources. You must also specify a Changer Device. If the Autochanger directive is set to No (default), the volume must be manually changed. You should also have an identical directive to the Storage resource in the Director's configuration file so that when labeling tapes you are prompted for the slot.

Changer Device = name-string

The specified name-string must be the generic SCSI device name of the autochanger that corresponds to the normal read/write Archive Device specified in the Device resource. This generic SCSI device name should be specified if you have an autochanger or if you have a standard tape drive and want to use the Alert Command (see below). For example, on Linux systems, for an Archive Device name of /dev/nst0, you would specify /dev/sg0 for the Changer Device name. Depending on your exact configuration, and the number of autochangers or the type of autochanger, what you specify here can vary. This directive is optional. See the Using Autochangers chapter of this manual for more details of using this and the following autochanger directives.

Changer Command = name-string

The name-string specifies an external program to be called that will automatically change volumes as required by Bacula. Normally, this directive will be specified only in the AutoChanger resource, which is then used for all devices. However, you may also specify the different Changer Command in each Device resource. Most frequently, you will specify the Bacula supplied mtx-changer script as follows:

Changer Command = "/path/mtx-changer %c %o %S %a %d"

and you will install the mtx on your system (found in the depkgs release). An example of this command is in the default bacula-sd.conf file. For more details on the substitution characters that may be specified to configure your autochanger please see the Autochangers chapter of this manual. For FreeBSD users, you might want to see one of the several chio scripts in examples/autochangers.

Alert Command = name-string

The name-string specifies an external program to be called at the completion of each Job after the device is released. The purpose of this command is to check for Tape Alerts, which are present when something is wrong with your tape drive (at least for most modern tape drives). The same substitution characters that may be specified in the Changer Command may also be used in this string. For more information, please see the Autochangers chapter of this manual.

Note, it is not necessary to have an autochanger to use this command. The example below uses the tapeinfo program that comes with the mtx package, but it can be used on any tape drive. However, you will need to specify a Changer Device directive in your Device resource (see above) so that the generic SCSI device name can be edited into the command (with the %c).

An example of the use of this command to print Tape Alerts in the Job report is:

Alert Command = "sh -c 'tapeinfo -f %c | grep TapeAlert'"

and an example output when there is a problem could be:

bacula-sd  Alert: TapeAlert[32]: Interface: Problem with SCSI interface
                  between tape drive and initiator.

Drive Index = number

The Drive Index that you specify is passed to the mtx-changer script and is thus passed to the mtx program. By default, the Drive Index is zero, so if you have only one drive in your autochanger, everything will work normally. However, if you have multiple drives, you must specify multiple Bacula Device resources (one for each drive). The first Device should have the Drive Index set to 0, and the second Device Resource should contain a Drive Index set to 1, and so on. This will then permit you to use two or more drives in your autochanger. As of Bacula version 1.38.0, using the Autochanger resource, Bacula will automatically ensure that only one drive at a time uses the autochanger script, so you no longer need locking scripts as in the past -- the default mtx-changer script works for any number of drives.

Autoselect = Yes|No

If this directive is set to yes (default), and the Device belongs to an autochanger, then when the Autochanger is referenced by the Director, this device can automatically be selected. If this directive is set to no, then the Device can only be referenced by directly using the Device name in the Director. This is useful for reserving a drive for something special such as a high priority backup or restore operations.

Maximum Changer Wait = time

This directive specifies the maximum time in seconds for Bacula to wait for an autochanger to change the volume. If this time is exceeded, Bacula will invalidate the Volume slot number stored in the catalog and try again. If no additional changer volumes exist, Bacula will ask the operator to intervene. The default is 5 minutes.

Maximum Rewind Wait = time

This directive specifies the maximum time in seconds for Bacula to wait for a rewind before timing out. If this time is exceeded, Bacula will cancel the job. The default is 5 minutes.

Maximum Open Wait = time

This directive specifies the maximum time in seconds for Bacula to wait for a open before timing out. If this time is exceeded, Bacula will cancel the job. The default is 5 minutes.

Always Open = Yes|No

If Yes (default), Bacula will always keep the device open unless specifically unmounted by the Console program. This permits Bacula to ensure that the tape drive is always available, and properly positioned. If you set AlwaysOpen to no Bacula will only open the drive when necessary, and at the end of the Job if no other Jobs are using the drive, it will be freed. The next time Bacula wants to append to a tape on a drive that was freed, Bacula will rewind the tape and position it to the end. To avoid unnecessary tape positioning and to minimize unnecessary operator intervention, it is highly recommended that Always Open = yes. This also ensures that the drive is available when Bacula needs it.

If you have Always Open = yes (recommended) and you want to use the drive for something else, simply use the unmount command in the Console program to release the drive. However, don't forget to remount the drive with mount when the drive is available or the next Bacula job will block.

For File storage, this directive is ignored. For a FIFO storage device, you must set this to No.

Please note that if you set this directive to No Bacula will release the tape drive between each job, and thus the next job will rewind the tape and position it to the end of the data. This can be a very time consuming operation. In addition, with this directive set to no, certain multiple drive autochanger operations will fail. We strongly recommend to keep Always Open set to Yes

Volume Poll Interval = time

If the time specified on this directive is non-zero, after asking the operator to mount a new volume Bacula will periodically poll (or read) the drive at the specified interval to see if a new volume has been mounted. If the time interval is zero (the default), no polling will occur. This directive can be useful if you want to avoid operator intervention via the console. Instead, the operator can simply remove the old volume and insert the requested one, and Bacula on the next poll will recognize the new tape and continue. Please be aware that if you set this interval too small, you may excessively wear your tape drive if the old tape remains in the drive, since Bacula will read it on each poll. This can be avoided by ejecting the tape using the Offline On Unmount and the Close on Poll directives. However, if you are using a Linux 2.6 kernel or other OSes such as FreeBSD or Solaris, the Offline On Unmount will leave the drive with no tape, and Bacula will not be able to properly open the drive and may fail the job. For more information on this problem, please see the description of Offline On Unmount in the Tape Testing chapter.

Close on Poll= Yes|No

If Yes, Bacula close the device (equivalent to an unmount except no mount is required) and reopen it at each poll. Normally this is not too useful unless you have the Offline on Unmount directive set, in which case the drive will be taken offline preventing wear on the tape during any future polling. Once the operator inserts a new tape, Bacula will recognize the drive on the next poll and automatically continue with the backup. Please see above more more details.

Maximum Open Wait = time

This directive specifies the maximum amount of time in seconds that Bacula will wait for a device that is busy. The default is 5 minutes. If the device cannot be obtained, the current Job will be terminated in error. Bacula will re-attempt to open the drive the next time a Job starts that needs the the drive.

Removable media = Yes|No

If Yes, this device supports removable media (for example, tapes or CDs). If No, media cannot be removed (for example, an intermediate backup area on a hard disk). If Removable media is enabled on a File device (as opposed to a tape) the Storage daemon will assume that device may be something like a USB device that can be removed or a simply a removable harddisk. When attempting to open such a device, if the Volume is not found (for File devices, the Volume name is the same as the Filename), then the Storage daemon will search the entire device looking for likely Volume names, and for each one found, it will ask the Director if the Volume can be used. If so, the Storage daemon will use the first such Volume found. Thus it acts somewhat like a tape drive -- if the correct Volume is not found, it looks at what actually is found, and if it is an appendable Volume, it will use it.

If the removable medium is not automatically mounted (e.g. udev), then you might consider using additional Storage daemon device directives such as Requires Mount, Mount Point, Mount Command, and Unmount Command, all of which can be used in conjunction with Removable Media.

Random access = Yes|No

If Yes, the archive device is assumed to be a random access medium which supports the lseek (or lseek64 if Largefile is enabled during configuration) facility. This should be set to Yes for all file systems such as DVD, USB, and fixed files. It should be set to No for non-random access devices such as tapes and named pipes.

Requires Mount = Yes|No

When this directive is enabled, the Storage daemon will submit a Mount Command before attempting to open the device. You must set this directive to yes for DVD-writers and removable file systems such as USB devices that are not automatically mounted by the operating system when plugged in or opened by Bacula. It should be set to no for all other devices such as tapes and fixed filesystems. It should also be set to no for any removable device that is automatically mounted by the operating system when opened (e.g. USB devices mounted by udev or hotplug). This directive indicates if the device requires to be mounted using the Mount Command. To be able to write a DVD, the following directives must also be defined: Mount Point, Mount Command, Unmount Command and Write Part Command.

Mount Point = directory

Directory where the device can be mounted. This directive is used only for devices that have Requires Mount enabled such as DVD or USB file devices.

Mount Command = name-string

This directive specifies the command that must be executed to mount devices such as DVDs and many USB devices. For DVDs, the device is written directly, but the mount command is necessary in order to determine the free space left on the DVD. Before the command is executed, %a is replaced with the Archive Device, and %m with the Mount Point.

Most frequently, for a DVD, you will define it as follows:

  Mount Command = "/bin/mount -t iso9660 -o ro %a %m"

However, if you have defined a mount point in /etc/fstab, you might be able to use a mount command such as:

  Mount Command = "/bin/mount /media/dvd"

See the Edit Codes section below for more details of the editing codes that can be used in this directive.

Unmount Command = name-string

This directive specifies the command that must be executed to unmount devices such as DVDs and many USB devices. Before the command is executed, %a is replaced with the Archive Device, and %m with the Mount Point.

Most frequently, you will define it as follows:

  Unmount Command = "/bin/umount %m"

See the Edit Codes section below for more details of the editing codes that can be used in this directive.

Minimum block size = size-in-bytes

On most modern tape drives, you will not need or want to specify this directive, and if you do so, it will be to make Bacula use fixed block sizes. This statement applies only to non-random access devices (e.g. tape drives). Blocks written by the storage daemon to a non-random archive device will never be smaller than the given size-in-bytes. The Storage daemon will attempt to efficiently fill blocks with data received from active sessions but will, if necessary, add padding to a block to achieve the required minimum size.

To force the block size to be fixed, as is the case for some non-random access devices (tape drives), set the Minimum block size and the Maximum block size to the same value (zero included). The default is that both the minimum and maximum block size are zero and the default block size is 64,512 bytes.

For example, suppose you want a fixed block size of 100K bytes, then you would specify:

 
    Minimum block size = 100K
    Maximum block size = 100K

Please note that if you specify a fixed block size as shown above, the tape drive must either be in variable block size mode, or if it is in fixed block size mode, the block size (generally defined by mt) must be identical to the size specified in Bacula -- otherwise when you attempt to re-read your Volumes, you will get an error.

If you want the block size to be variable but with a 64K minimum and 200K maximum (and default as well), you would specify:

 
    Minimum block size = 64K
    Maximum blocksize = 200K

Maximum block size = size-in-bytes

On most modern tape drives, you will not need to specify this directive. If you do so, it will most likely be to use fixed block sizes (see Minimum block size above). The Storage daemon will always attempt to write blocks of the specified size-in-bytes to the archive device. As a consequence, this statement specifies both the default block size and the maximum block size. The size written never exceed the given size-in-bytes. If adding data to a block would cause it to exceed the given maximum size, the block will be written to the archive device, and the new data will begin a new block.

If no value is specified or zero is specified, the Storage daemon will use a default block size of 64,512 bytes (126 * 512).

Hardware End of Medium = Yes|No

If No, the archive device is not required to support end of medium ioctl request, and the storage daemon will use the forward space file function to find the end of the recorded data. If Yes, the archive device must support the ioctl MTEOM call, which will position the tape to the end of the recorded data. In addition, your SCSI driver must keep track of the file number on the tape and report it back correctly by the MTIOCGET ioctl. Note, some SCSI drivers will correctly forward space to the end of the recorded data, but they do not keep track of the file number. On Linux machines, the SCSI driver has a fast-eod option, which if set will cause the driver to lose track of the file number. You should ensure that this option is always turned off using the mt program.

Default setting for Hardware End of Medium is Yes. This function is used before appending to a tape to ensure that no previously written data is lost. We recommend if you have a non-standard or unusual tape drive that you use the btape program to test your drive to see whether or not it supports this function. All modern (after 1998) tape drives support this feature.

Fast Forward Space File = Yes|No

If No, the archive device is not required to support keeping track of the file number (MTIOCGET ioctl) during forward space file. If Yes, the archive device must support the ioctl MTFSF call, which virtually all drivers support, but in addition, your SCSI driver must keep track of the file number on the tape and report it back correctly by the MTIOCGET ioctl. Note, some SCSI drivers will correctly forward space, but they do not keep track of the file number or more seriously, they do not report end of medium.

Default setting for Fast Forward Space File is Yes.

Use MTIOCGET = Yes|No

If No, the operating system is not required to support keeping track of the file number and reporting it in the (MTIOCGET ioctl). The default is Yes. If you must set this to No, Bacula will do the proper file position determination, but it is very unfortunate because it means that tape movement is very inefficient. Fortunately, this operation system deficiency seems to be the case only on a few *BSD systems. Operating systems known to work correctly are Solaris, Linux and FreeBSD.

BSF at EOM = Yes|No

If No, the default, no special action is taken by Bacula with the End of Medium (end of tape) is reached because the tape will be positioned after the last EOF tape mark, and Bacula can append to the tape as desired. However, on some systems, such as FreeBSD, when Bacula reads the End of Medium (end of tape), the tape will be positioned after the second EOF tape mark (two successive EOF marks indicated End of Medium). If Bacula appends from that point, all the appended data will be lost. The solution for such systems is to specify BSF at EOM which causes Bacula to backspace over the second EOF mark. Determination of whether or not you need this directive is done using the test command in the btape program.

TWO EOF = Yes|No

If Yes, Bacula will write two end of file marks when terminating a tape -- i.e. after the last job or at the end of the medium. If No, the default, Bacula will only write one end of file to terminate the tape.

Backward Space Record = Yes|No

If Yes, the archive device supports the MTBSR ioctl to backspace records. If No, this call is not used and the device must be rewound and advanced forward to the desired position. Default is Yes for non random-access devices. This function if enabled is used at the end of a Volume after writing the end of file and any ANSI/IBM labels to determine whether or not the last block was written correctly. If you turn this function off, the test will not be done. This causes no harm as the re-read process is precautionary rather than required.

Backward Space File = Yes|No

If Yes, the archive device supports the MTBSF and MTBSF ioctls to backspace over an end of file mark and to the start of a file. If No, these calls are not used and the device must be rewound and advanced forward to the desired position. Default is Yes for non random-access devices.

Forward Space Record = Yes|No

If Yes, the archive device must support the MTFSR ioctl to forward space over records. If No, data must be read in order to advance the position on the device. Default is Yes for non random-access devices.

Forward Space File = Yes|No

If Yes, the archive device must support the MTFSF ioctl to forward space by file marks. If No, data must be read to advance the position on the device. Default is Yes for non random-access devices.

Offline On Unmount = Yes|No

The default for this directive is No. If Yes the archive device must support the MTOFFL ioctl to rewind and take the volume offline. In this case, Bacula will issue the offline (eject) request before closing the device during the unmount command. If No Bacula will not attempt to offline the device before unmounting it. After an offline is issued, the cassette will be ejected thus requiring operator intervention to continue, and on some systems require an explicit load command to be issued (mt -f /dev/xxx load) before the system will recognize the tape. If you are using an autochanger, some devices require an offline to be issued prior to changing the volume. However, most devices do not and may get very confused.

If you are using a Linux 2.6 kernel or other OSes such as FreeBSD or Solaris, the Offline On Unmount will leave the drive with no tape, and Bacula will not be able to properly open the drive and may fail the job. For more information on this problem, please see the description of Offline On Unmount in the Tape Testing chapter.

Maximum Volume Size = size

No more than size bytes will be written onto a given volume on the archive device. This directive is used mainly in testing Bacula to simulate a small Volume. It can also be useful if you wish to limit the size of a File Volume to say less than 2GB of data. In some rare cases of really antiquated tape drives that do not properly indicate when the end of a tape is reached during writing (though I have read about such drives, I have never personally encountered one). Please note, this directive is deprecated (being phased out) in favor of the Maximum Volume Bytes defined in the Director's configuration file.

Maximum File Size = size

No more than size bytes will be written into a given logical file on the volume. Once this size is reached, an end of file mark is written on the volume and subsequent data are written into the next file. Breaking long sequences of data blocks with file marks permits quicker positioning to the start of a given stream of data and can improve recovery from read errors on the volume. The default is one Gigabyte. This directive creates EOF marks only on tape media. However, regardless of the medium type (tape, disk, DVD, ...) each time a the Maximum File Size is exceeded, a record is put into the catalog database that permits seeking to that position on the medium for restore operations. If you set this to a small value (e.g. 1MB), you will generate lots of database records (JobMedia) and may significantly increase CPU/disk overhead.

Note, this directive does not limit the size of Volumes that Bacula will create regardless of whether they are tape or disk volumes. It changes only the number of EOF marks on a tape and the number of block positioning records (see below) that are generated. If you want to limit the size of all Volumes for a particular device, use the Maximum Volume Size directive (above), or use the Maximum Volume Bytes directive in the Director's Pool resource, which does the same thing but on a Pool (Volume) basis.

Block Positioning = yes|no

This directive tells Bacula not to use block positioning when doing restores. Turning this directive off can cause Bacula to be extremely slow when restoring files. You might use this directive if you wrote your tapes with Bacula in variable block mode (the default), but your drive was in fixed block mode. The default is yes.

Maximum Network Buffer Size = bytes

where bytes specifies the initial network buffer size to use with the File daemon. This size will be adjusted down if it is too large until it is accepted by the OS. Please use care in setting this value since if it is too large, it will be trimmed by 512 bytes until the OS is happy, which may require a large number of system calls. The default value is 32,768 bytes.

The default size was chosen to be relatively large but not too big in the case that you are transmitting data over Internet. It is clear that on a high speed local network, you can increase this number and improve performance. For example, some users have found that if you use a value of 65,536 bytes they get five to ten times the throughput. Larger values for most users don't seem to improve performance. If you are interested in improving your backup speeds, this is definitely a place to experiment. You will probably also want to make the corresponding change in each of your File daemons conf files.

Maximum Spool Size = bytes

where the bytes specify the maximum spool size for all jobs that are running. The default is no limit.

Maximum Job Spool Size = bytes

where the bytes specify the maximum spool size for any one job that is running. The default is no limit. This directive is implemented only in version 1.37 and later.

Spool Directory = directory

specifies the name of the directory to be used to store the spool files for this device. This directory is also used to store temporary part files when writing to a device that requires mount (DVD). The default is to use the working directory.

Maximum Part Size = bytes

This is the maximum size of a volume part file. The default is no limit. This directive is implemented only in version 1.37 and later.

If the device requires mount, it is transferred to the device when this size is reached. In this case, you must take care to have enough disk space left in the spool directory.

Otherwise, it is left on the hard disk.

It is ignored for tape and FIFO devices.

Edit Codes for Mount and Unmount Directives

Before submitting the Mount Command, Unmount Command, Write Part Command, or Free Space Command directives to the operating system, Bacula performs character substitution of the following characters:

    %% = %
    %a = Archive device name
    %e = erase (set if cannot mount and first part)
    %n = part number
    %m = mount point
    %v = last part name (i.e. filename)

Devices that require a mount (DVD)

All the directives in this section are implemented only in Bacula version 1.37 and later and hence are available in version 1.38.6.

As of version 1.39.5, the directives "Requires Mount", "Mount Point", "Mount Command", and "Unmount Command" apply to removable filesystems such as USB in addition to DVD.

Requires Mount = Yes|No

You must set this directive to yes for DVD-writers, and to no for all other devices (tapes/files). This directive indicates if the device requires to be mounted to be read, and if it must be written in a special way. If it set, Mount Point, Mount Command, Unmount Command and Write Part Command directives must also be defined.

Mount Point = directory

Directory where the device can be mounted.

Mount Command = name-string

Command that must be executed to mount the device. Before the command is executed, %a is replaced with the Archive Device, and %m with the Mount Point.

Most frequently, you will define it as follows:

  Mount Command = "/bin/mount -t iso9660 -o ro %a %m"

Unmount Command = name-string

Command that must be executed to unmount the device. Before the command is executed, %a is replaced with the Archive Device, and %m with the Mount Point.

Most frequently, you will define it as follows:

  Unmount Command = "/bin/umount %m"

Write Part Command = name-string

Command that must be executed to write a part to the device. Before the command is executed, %a is replaced with the Archive Device, %m with the Mount Point, %e is replaced with 1 if we are writing the first part, and with 0 otherwise, and %v with the current part filename.

For a DVD, you will most frequently specify the Bacula supplied dvd-handler script as follows:

  Write Part Command = "/path/dvd-handler %a write %e %v"

Where /path is the path to your scripts install directory, and dvd-handler is the Bacula supplied script file. This command will already be present, but commented out, in the default bacula-sd.conf file. To use it, simply remove the comment (#) symbol.

Free Space Command = name-string

Command that must be executed to check how much free space is left on the device. Before the command is executed,%a is replaced with the Archive Device, %m with the Mount Point, %e is replaced with 1 if we are writing the first part, and with 0 otherwise, and %v with the current part filename.

For a DVD, you will most frequently specify the Bacula supplied dvd-handler script as follows:

  Free Space Command = "/path/dvd-handler %a free"

Where /path is the path to your scripts install directory, and dvd-handler is the Bacula supplied script file. If you want to specify your own command, please look at the code of dvd-handler to see what output Bacula expects from this command. This command will already be present, but commented out, in the default bacula-sd.conf file. To use it, simply remove the comment (#) symbol.

If you do not set it, Bacula will expect there is always free space on the device.

Kern Sibbald 2009-02-06