Device Resource
The Device Resource specifies the details of each device 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 system 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 storage device. In the case of a tape device, it can be, for example /dev/nst0 or /dev/rmt/0mbn . 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 node name of a tape drive, but you may also specify an absolute path to an existing directory for disk storage device types like File, Aligned, Dedup and Cloud plugin local cache. If the device is a disk device Bacula will write to file storage in the specified directory, and the filename used (a directory name in the case of Cloud volumes) will be the Volume name as specified in the Catalog.
In the case of disk storages, where volumes are written to disk, all of the devices in the Autochanger must point to the same 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.
Aligned Tells Bacula that the device is special Aligned Device. See the specific Aligned User’s guide for more information.
Dedup The device is a Deduplication device. The Storage Daemon will use the deduplication engine. Please see the specific Deduplication User’s guide for more information.
Cloud The device is a Cloud device. The Storage Daemon will use the Cloud to upload/download volumes. Please see the specific Cloud User’s guide for more information.
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. 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.
Cloud = <name-string> A Device’s new Cloud directive specifies a Cloud resource. As with other Bacula resource specifications, this directive specifies the name of the Cloud resource that this device will use.
Example:
Cloud = MyCloud
Enabled = <yes|no> This directive allows you to enable or disable the resource.
Media Type = <name-string> The specified name-string names the type of media supported by this device, for example, “LTO-8”. 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 “LTO-8” then during the restore, Bacula will be able to choose any Storage Daemon that handles “LTO-8”. 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 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 = "/opt/bacula/scripts/mtx-changer"
and you will install the mtx program on your system. 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, see the Autochangers chapter. For FreeBSD users, you might want to see one of the several chio scripts in examples/autochangers.
Bacula supports ANSI or IBM tape labels as long as you enable it. In fact, with the proper configuration, you can force Bacula to require ANSI or IBM labels. Bacula can create an ANSI or IBM label, but if Check Labels is enabled (see below), Bacula will look for an existing label, and if it is found, it will keep the label. Consequently, you can label the tapes with programs other than Bacula, and Bacula will recognize and support them. Even though Bacula will recognize and write ANSI and IBM labels, it always writes its own tape labels as well. When using ANSI or IBM tape labeling, you must restrict your Volume names to a maximum of six characters. If you have labeled your Volumes outside of Bacula, then the ANSI/IBM label will be recognized by Bacula only if you have created the HDR1 label with BACULA.DATA in the Filename field (starting with character 5). If Bacula writes the labels, it will use this information to recognize the tape as a Bacula tape. This allows ANSI/IBM labeled tapes to be used at sites with multiple machines and multiple backup pro- grams.
Label Type = ANSI | IBM | Bacula This directive is implemented in the Director Pool resource and in the SD Device resource. If it is specified in the the SD Device resource, it will take precedence over the value passed from the Director to the SD.
Check Label = <yes|No> If yes, Bacula Storage Daemon will check the label type when reading a tape volume. It can be used when the pool contains a mix of IBM/ANSI and Bacula volumes.
Control Device = <name-string> The control device is the SCSI control device
that corresponds to the Archive Device. The correspondance can be done via the
lssci -g command.
/opt/bacula# lsscsi -g
[1:0:0:0] tape HP Ultrium 4-SCSI H61W /dev/st0 /dev/sg0
[1:0:0:1] tape HP Ultrium 4-SCSI H61W /dev/st1 /dev/sg1
[1:0:0:2] mediumx HP MSL G3 Series E.00 - /dev/sg2
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, see the Autochangers chapter.
The directive in the Device resource can call the tapealert script that is installed in the scripts directory. It is defined as follows:
Device {
Name = ...
Archive Device = /dev/nst0
Alert Command = "/opt/bacula/scripts/tapealert %l"
Control Device = /dev/sg1 # must be SCSI ctl for /dev/nst0
...
}
Once the above mentioned two directives (Alert Command and ControlDevice) are in place in each of your resources, Bacula will check for tape alerts at two points:
After the Drive is used and it becomes idle.
After each read or write error on the drive.
At each of the above times, Bacula will call the new tapealert script, which
uses the tapeinfo program. The tapeinfo utility is part of the apt
sg3-utils and rpm sg3_utils packages. Then for each tape alert that
Bacula finds for that drive, it will emit a Job message that is either INFO,
WARNING, or FATAL depending on the designation in the
Tape Alert published by the T10 Technical Committee on SCSI Storage
Interfaces. For the specification, see:
http://www.t10.org/ftp/t10/document.02/02-142r0.pdf
Worm Command = <name-string> The name-string specifies an external program
to be called when loading a new volume. The purpose of this command is to check if
the current tape is a WORM tape. The same substitution characters that may be
specified in the Changer Command ay also be used in this string.
The directive in the resource can call the isworm script that is installed in the scripts directory. It is defined as follows:
Device {
Name = ...
Archive Device = /dev/nst0
Worm Command = "/opt/bacula/scripts/isworm %l"
Control Device = /dev/sg1 # must be SCSI ctl for /dev/nst0
...
}
Bacula will call the isworm script, which uses the tapeinfo and sdparm program.
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. 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 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 Concurrent Jobs = <num> Maximum Concurrent Jobs is a directive that permits setting the maximum number of Jobs that can run concurrently on a specified Device. Using this directive, it is possible to have different Jobs using multiple drives, because when the Maximum Concurrent Jobs limit is reached, the Storage Daemon will start new Jobs on any other available compatible drive. This facilitates writing to multiple drives with multiple Jobs that all use the same Pool.
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 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.
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. 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, no polling will occur. The default value is 5 mins. 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.
Volume Encryption = <No|yes|strong> This directive allows you to enable the encryption for the given File device. The default is No.
The encryption can be of 3 different types:
no This is the default, the device don’t do any encryption.
yes The device encrypts the data, but all information in the volume label are left in clear text.
strong The device encrypts the data, and obfuscate any information in the volume label except the one that are needed for the management of the volume. The fields that are obfuscate are: volume name.
The encryption keys are given by the key manager program specified by the Encryption Command directive in the Storage resource. More information can be found in the Volume Encryption 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.
Sync On Close = <yes|No> If yes, Bacula will sync the device at the end of each job and when closing the device. Normally it might be useful if you store the data on network filesystems. The default value is yes.
Set Volume Read Only = <yes|No>
Warning
Only for file-based devices.
If yes, this device sets the permission of the volume file for each volume
when setting it’s status to ‘Full’. Permissions are set back when the volume is
relabeled/truncated. The Access Time (atime) file attribute is updated with the
maximum value between the Device MinimumVolumeProtectionTime and the Volume
Retention.
When this directive is combined with the NetApp SnapLock, DataDomain or HPE
StoreOnce immutable feature and the volume is Full, there is no other way than
to wait for the MinimumVolumeProtectionTime or VolumeRetention to
expire so that the volume can be relabeled/reused. The default is no.
Set Volume Immutable = <yes|No>
Warning
Only for file-based devices.
This feature can only be used if Bacula is run as a systemd service because only then, with proper capabilities set for the daemon, it’s allowed to manage files attributes of Bacula Volumes.
If yes, this device sets the ‘Immutable’ file attribute for each volume when setting it’s status to ‘Full’. Attribute is cleared when the volume is relabeled/truncated.
When this directive is set and the volume is Full, there is no other way than
to wait for the MinimumVolumeProtectionTime’ or VolumeRetention to
expire so that the volume can be relabeled/reused. The default is no.
Set Volume Append Only = <yes|No>
Warning
Only for file-based devices.
This feature can only be used if Bacula is run as a systemd service because only then, with proper capabilities set for the daemon, it’s allowed to manage file attributes of Bacula Volumes.
If yes, this device sets the Append_Only file attribute for each
volume that is created (either automatically or using the label command), at
the moment of writing first backup job. Attribute is cleared when the volume is
relabeled/truncated. The default is no.
Minimum Volume Protection Time
Minimum Volume Protection Time = <time-interval>
Warning
Only for file-based devices.
This feature can only be used if Bacula is run as a systemd service because only then, with proper capabilities set for the daemon, it’s allowed to manage Volume Files’ attributes.
This directive defines the minimum interval of time in which the Storage Daemon
respects the ‘Immutable’ file attribute which is set when marking volume as
Full. Bacula won’t allow relabeling or reusing such a volume before this period
expires. When applied, the Storage Daemon may use the VolumeRetention if
it is more protective.
When this directive is set to 0, the drive device will not be able to truncate/relabel volumes at all, effectively keeping volumes all the time for further usage.
The default is 30 days.
Removable Media = <yes|no> If yes, this device supports removable media (for example, tapes). 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 hard disk. 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 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 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 devices need a mount, the following directives must also be defined: Mount Point, Mount Command, and Unmount 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 USB file devices.
Mount Command = <name-string> This directive specifies the command that must be executed to mount devices such as many USB devices. Before the command is executed, %a is replaced with the Archive Device, and %m with the Mount Point.
See the Edit Codes section below for more details of the editing codes that can be used in this directive.
If you need to specify multiple commands, create a shell script.
Unmount Command = <name-string> This directive specifies the command that must be executed to unmount devices such as 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
See the Edit Codes section below for more details of the editing codes that can be used in this directive.
If you need to specify multiple commands, create a shell script.
Block Checksum = <yes|no> You may turn off the Block Checksum (CRC32) code that Bacula uses when writing blocks to a Volume. Doing so can reduce the Storage daemon CPU usage slightly. It will also permit Bacula to read a Volume that has corrupted data.
The default is yes– i.e. the checksum is computed on write and checked on read.
We do not recommend to turn this off particularly on older tape drives or for disk Volumes where doing so may allow corrupted data to go undetected.
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 256K maximum (and default as well), you would specify:
Minimum block size = 64K
Maximum blocksize = 256K
The Device Minimum and Maximum Block Size directives must correspond to the settings used to write volumes in order to read them back correctly during a restore
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 reduce shoe-shine and improve performance on more modern LTO drives. 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 exceeds 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).
The maximum size-in-bytes possible is 4,000,000.
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 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 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 ioctl s 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.
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 50GB 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 Pool resource 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, USB …) each time
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.
If you are configuring an LTO-7 or LTO-8 tape, you probably will want to set the
Maximum File Size to 5GB or bigger to avoid making the drive stop to write an EOF mark.
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 Maximum Volume Bytes the directive in the Director’s Pool resource, which does the same thing but on a Pool (Volume) basis.
Maximum File Index = <size> Some data might include information about the actual position of
a block in the data stream. This information is stored in the catalog inside the table.
By default, one index record will be created every 100MB of data. The index permits quicker
positioning to the start of a given block in the Bacula Volume and can improve the
Single Item Restore feature. If you set this to a small value (e.g. 1MB), you will generate
lots of database records (FileMedia) and may significantly increase CPU/disk overhead.
Maximum Part Size = <size> This directive allows one to specify the maximum size for each part file of a cloud volume. Smaller part sizes will reduce restore costs, but may require a small additional overhead to handle multiple parts. The maximum number of parts permitted in a Cloud Volume is 524,288. The maximum size of any given part is approximately 17.5TB.
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 maximum value is 1,000,000 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.
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 (USB). The default is to use the working directory .
Use LinTape = <yes|no> If yes, the archive device must use the IBM Lintape Kernel
interface instead of the standard ST Linux Kernel module. The Use MTIOCGET = No should
be used when using the Lintape module. The default is no, the use of the default ST
Linux Kernel module is recommended.
Label Media = <yes|no> If yes, permits this device to automatically label blank media without an explicit operator command. It does so by using an internal algorithm as defined on the Label Format record in each Pool resource. If this is no as by default, Bacula will label tapes only by specific operator command (label in the Console) or when the tape has been recycled. The automatic labeling feature is most useful when writing to disk rather than tape volumes.
Automatic mount = <yes|no> If yes (the default), permits the daemon to examine the device to determine if it contains a Bacula labeled volume. This is done initially when the daemon is started, and then at the beginning of each job. This directive is particularly important if you have set Always Open = no because it permits Bacula to attempt to read the device before asking the system operator to mount a tape. However, please note that the tape must be mounted before the job begins.
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 (USB)
The directives “Requires Mount”, “Mount Point”, “Mount Command”, and “Unmount Command” apply to removable filesystems such as USB.
Requires Mount = <yes|no> You must set this directive to yes for removable devices such as USB unless they are automatically mounted, and to no for all other devices (tape/disk). 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 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"
For some media, you may need multiple commands. If so, it is recommended that you use a shell script instead of putting them all into the Mount Command. For example, instead of this:
Mount Command = "/usr/local/bin/mymount"
Where that script contains:
#!/bin/sh
ndasadmin enable -s 1 -o w
sleep 2
mount /dev/ndas-00323794-0p1 /backup
Similar consideration should be given to all other Command parameters.
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"
If you need to specify multiple commands, create a shell script.
See also
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