server.conf - server side configuration file for afbackup
This file needs not be edited by hand with an editor, instead the
program /usr/sbin/afserverconfig can be used. If you are running X, the
programs are the same, but start with an ’x’; (Tcl/Tk must be
installed): and /usr/sbin/xafserverconfig. The parameters described
below are the same for both versions. Entries consist of lines
starting with the parameter name, then follows a colon and the value of
the parameter. Comment lines can be inserted as desired starting with
the # character.
This is the device the backup is written to. It can be any tape
device with the capability to distinguish between several files
on the media. It is mandatory to supply the no-rewind device
here, otherwise this package won’t work properly. Suitable
device names for some OS-es:
Digital UNIX: /dev/nrmt0h
If the drive has a media handler attached, a specifier for this
may follow the device name. The format for this is =<drive-
count>@<device>#<num-slots>^<num-loadbays> , for example
=1@/dev/sg0#6^2 . Whitespace before and following the special
characters = @ and # is allowed for readability. The example
means: The drive is number 1 in the changer, /dev/sg0 is the
changer device, that has 6 media slots and 2 loadbays. The parts
=<drive-count> and ^<num-loadbays> are optional.
If the server is only used for remote start and no real backup
device should be accessed, a dash - should be configured here as
device, so a respective warning to the server log will be
The identifier for the server. Default: The official hostname,
followed by a colon and the full path to the configuration file.
The server identifier can be used to become independent of the
server machine name. This might be helpful, if the backup server
should move to another machine. Whitespace characters may be
used in this identifier, but they are replaced with asterisks *
before comparing, so they are not significant
The blocksize of the tape device. This value specifies how many
bytes are written to tape or read from it with one system call.
Usually this value is at least 512 or a multiple of it. It is
not very important if the blocksize is set to 2048 or 1024. The
main thing to keep in mind is that if there is a minimum, it
should be respected (e.g. 1024 on AIX), otherwise media space is
Three numbers and a filename can be given here. The first number
is the desired size of the tape buffer in bytes. The optional
second number is the high-watermark while writing in percent
(default: 67), the optional third number is the low watermark,
also in percent (default: 0). As long as the buffer fill rate
does not reach the high watermark, nothing is written, but when
it is reached, writing does not stop until the buffer fill rate
is equal or below the low watermark. This procedure hopefully
reduces tape wear and increases average writing speed, because
excessive tape stops/starts are avoided. If the optional
filename is given, buffering is done in the given file, which is
mapped into the server’s address space for that purpose. In the
filename, patterns are replaced like with Changer-Configuration-
This value must be 1 or 0, which means, that you either have a
cartridge handling system (i.e. some kind of robot) (1) or not
(0). If you don’t have a robot, you may nonetheless maintain a
set of cartridges, that you will have to manually number. The
backup server side will inform you via email or console output,
whenever another cartridge has to be inserted into the drive and
what number it requires it is.
Number Of Cartridges
This number specifies, how many cartridges you are maintaining.
If you have a cartridge handling system (some kind of robot),
this is usually the number of cartridges, your system is
Several cartridge sets can be used. Here they can be specified.
The specifiers for the cartridge sets must be separated by
whitespace. Each specifier may consist of digits, commas and
dashes. Examples for cartridge set specifiers: 1-5 7-9,12
6,10,11 . This example shows how to specify three cartridge
sets. If the access to a cartridge set should be allowed only
for certain clients, this may specified with a colon immediately
following the set specifier without whitespace, followed by one
of three forms: Either a list of hostnames, separated by commas
and no whitespace inbetween, or the full path to a file
containing the hostnames one per line, or by a command to be
executed. The command must start with a bar | and must be
enclosed in double quotes, if it is containing whitespace. If %H
occurres in the command it will be replaced with the client
name, who wants to gain access to the cartridge set. The command
must exit with a status of 0, if access is to be granted,
otherwise with an exit status unequal to 0. The name of the host
to be checked is also written to standard input of this command,
so %H needs not to be used. Examples specifying cartridge sets
with restricted access:
9-15:"| fgrep .my.domain.com"
Remember, that grep will exit with 0, if a match has been found,
otherwise 1. Note, that localhost and the network name of the
machine should be both given, if the server is also a client.
The names to be supplied here are not the client IDs configured
on the client side, but the network names of the machines.
If this parameter is not given, there is only the default set
number 1 with all available cartridges, access is permitted to
any client. Not all cartridges need to be included in a set and
sets must not overlap.
Max Bytes Per File
The stream of data, that represents your backup, is divided into
pieces (files on tape). This is done to find the files faster
during a restore. This value determines, how large the pieces on
tape may be in bytes. Some good values for a few tape
Max Bytes Per Tape
With this entry the number of bytes written to a single tape can
be limited. Serveral entries with a leading range specifier
allow to handle certain tapes differently. The range specifier
must end in a colon : and may contain lists of ranges and
numbers. A given number without a leading range specifier will
be valid for all tapes not explicitly described. Default is use
of full tape capacity. Several entries must be separated by
whitespace and may look like the following examples:
4000000000 1,3-5:3500000000 7,9-:5000000000
This means: 3.5 GB for cartridges 1 and 3 through 5, 5 GB for
cartridges 7 and 9 up to the last cartridge, 4 GB for the rest.
Full Append Mode
Normally, when the insert (writing) position is forced to
another tape with the cartis command or with the clientside
option -G, the rest of the current tape remains unused. When
this option is set to 1, it will nonetheless be used to write
data on, if there is no free tape left.
Variable Append Mode
In default mode, the place (tape and tapefile), where the next
data will be written, is fix and can only manipulated using the
command cartis or the clientside option -G. When the server
wants to write with variable append mode enabled, any cartridge,
that is in the drive, is belonging to the right cartridge set
and is allowed to be written, will be accepted and appended to.
Note, that this will also override the settings of cartis or
Reject Unlabeled Tapes
Default is to accept an unlabeled tape as the requested one and
to label it automatically. If this behaviour is unwanted and
only tapes with a recognized label should be permitted for
writing, this parameter should be set.
When a tape gets full and another one must be chosen to continue
writing, the server does not make a difference, whether a tape
is available in a changer or not, if this flag is not set. This
is the default. If this parameter is set, the next cartridge is
chosen from those, that are available in the slots of a changer,
if present and configured. If there is no tape found inside the
changer, that is allowed to be overwritten, manual administrator
interaction is nonetheless required.
This is the time in seconds, the program waits after another
cartridge has been put into the drive. Normal devices need a
certain time span to mount the tape to get it ready for use.
Normally this value is not critical. If you estimate it too low,
the ioctl-system-call will wait until the device becomes
available. This time is sometimes longer than two minutes, so if
you want to proceed quickly after a cartridge change, you may
measure the maximum time your system needs. Some tried values
for a few tape technologies:
If the streaming device is not accessible (i.e. an open or a
tape handling command fails) or another backup server process is
still running, the server process re-tries his attempts
regularly. If it fails longer than the time in minutes supplied
here, an e-mail is sent to the configured user in charge (see:
User To Inform). Supplying 0 means: never send mail.
Same as Device-Unavailable-Send-Mail-After-Min, but this time
not an e-mail is sent, but the server process exits silently
leaving a warning in the log file. Supplying 0 means: try
forever, never exit.
This is the interval in seconds, after that regularly the device
is probed to be ready for reading. Thus after having ejected a
cartridge it is automatically recognized, if a new cartridge has
been inserted. For other media (e.g. exchangeable disks) this
may not be suitable. Supply a 0 in these cases for no probing.
This is the (shell-) command to run to position the tape to a
certain file. Usually this is something like a combination of:
mt -f <device> rewind and mt -f <device> fsf <number>. If the
command you are supplying here starts to count with 1 for the
first file on tape, you should insert %n for the <number>. If it
starts with 0, replace <number> with %m. If you don’t want to
type the devicename again here, you may write %d instead.
This is the (shell-) command to run to skip over to a file later
on tape. Usually this is something like
mt -f <device> fsf <number> Insert %n, where the number of
files to skip over must be supplied in the command, in the
example instead of <number>, and %d, where the device should
appear (here: <device>).
This is the (shell-) command to run to put a certain cartridge
into the device. If the command you are supplying here starts to
count with 1 for the first cartridge, you should insert %n in
the place, where the cartridge number must appear. If it starts
with 0, replace it with %m. If you don’t want to type the
devicename again here, you may write %d instead. If you don’t
have a command to perform this task, don’t supply anything here.
In this case you must set your cartridge handling system to
sequential mode (automatically putting the next cartridge in,
when the current one is ejected).
This is the (shell-) command to run to eject a cartridge
currently placed inside the streamer device. This is normally
something like mt -f <device> rewoffl (but better consult your
man-pages). You have to supply this either if you have no
cartridge handling system (robot) or if you have no command to
set the cartridge directly by number. In the latter case this
package tries to maintain the number of the current cartridge in
a file and to (hopefully) keep it consistent with the reality.
In this case the cartridge handling system must be configured to
sequential mode (automatically putting the next cartridge in,
when the current one is ejected). The pattern %c, if used in
this command, will be replaced with number of the current
cartridge, %n with the number of the next one, that is expected
to be put into the streamer by a robot in sequential mode. %b
can be used instead of %c if counting of cartridges starts with
0 and not with 1. The same applies for %m, what means %n minus
1. %d is replaced with the device name.
The (shell-) command, the server runs before accessing the
storage media for the first time or after changing it. %d will
be replaced with the device. This command can be used e.g. to
automatically mount a removable disk after inserting. This
command might be called several times on the same media, this
has to kept in mind when configuring it. %n is replaced with the
number of the cartridge, that is expected to in the drive, when
the next media access operation will take place. %m is replaced
with %n - 1 i.e. assuming that the cartridge numbering starts
with zero, not one. Note, that the cartridge, that will really
be in the drive is not necessarily known at the time, the Init-
Media-Command is running. Thus the term "expected".
The (shell-) command to run, if the tape must be erased.
(actually not needed).
The (shell-) command to run, when a tape is full. %d is replaced
with the device name, %c with the number of the cartridge, that
became full, %n with the number of cycles, the cartridge has
become full until now and %C with the full path to the
User To Inform
If you don’t have a cartridge handling system (robot), a human
maintainer must put the appropriate cartridge into the tape
device. If you supply a mail program, an e-mail is sent to the
user given here, which informs him, that and which cartridge (by
number) must be put into the tape device. If a timespan is
configured, after that an automatic e-mail should be sent due to
an unaccessible tape device, it is directed to this user (see
The mail program used to send messages to a human maintainer.
This is done, whenever another cartridge must be put into the
tape device and it can’t be done automatically (by a robot or
whatever). If you don’t want to type the username again here,
you can instead write %u . The pattern %U will be replaced with
the login name of a current user on the client side, %H with the
name of the client host. If none could be figured out, the
entire word containing %U or %H is deleted from the command. If
you don’t want mails to be sent, you may instead supply any
other command, that reads the standard input and does something
reasonable with it, e.g. redirects it to the console:
cat > /dev/console
The directory, where varying files should be put in. These files
should not be deleted. The information they contain is necessary
for the server to work properly
In this file some values are stored, e.g. the number of the
cartridge currently placed inside the streamer device.
Logging information concerning errors or other notable events is
redirected to this file. If the first word of this entry is
starting with @, then logging is directed to the syslog as well.
If there are characters immediately following the @, this word
is used as the syslog identifier, otherwise the identifier is
afbackup. If writing to the syslog is configured, the rest of
the entry is used as additional logging file, if present.
The current status of the server is written to this file. If it
starts with >>, then the file is created and status messages
will be appended to it. Otherwise the file is removed before
writing. %V in the filename is replaced with the configured Var-
To prevent the server program from being started several times a
lock file is created and this is it’s name.
Entries specifying files, that contain encryption keys for
authenticating backup clients to the server. Each entry consists
of a filename, optionally followed by a colon : and a specifier
for client selection. If an entry lacks a client selector, this
one will apply for all clients, that are not matched by any
other entry. The client selector is either a list of comma-
separated hostnames, a filename starting with a slash /
containing hostnames one per line, or a command starting with a
bar, that is stripped off before starting the command. The
command gets the current client name as input on stdin, aside
from arguments containing patterns (see below). If the command
returns an exit status of 0, the client name will match the
entry. Entries are separated by whitespace. If an entry must
contain whitespace, it must be enclosed by double quotes. If
colons are needed within the filenames, they must be escaped
using a backslash. Each key file must contain at least 5
characters and must not have read permission for group or world.
The pattern %H is replaced with the client name resolved from
the IP-address. %h is similar to %H, but everything from and
including the first dot is stripped off. For more pattern
replacements see: Status-file.
If you are using the remote start option for backing up clients,
this is the directory, where programs must reside, that can be
started remotely. No other programs can be started remotely (for
Here you may supply a (shell-) command to be run, when the
backup server side wakes up, i.e. the server process starts. A
%p appearing in this command is replaced with the name of the
client, that connected the backup service.
Here you may supply a (shell-) command to be run, when the
backup server side goes to sleep, i.e. the server process ends.
A %p appearing in this command is replaced with the name of the
client, that connected the backup service.
Server configuration file
The directory for logging the server actions
Some internal state information of the server.
afclientconfig(8), xafclientconfig(8), full_backup(8), incr_backup(8),
afverify(8), afrestore(8), xafrestore(8), update_indexes(8),
copy_tape(8), afclient.conf(8), afserver(8), afmserver(8),
afserver.conf(8), cartis(8), cartready(8), label_tape(8), tar(1)
afbackup was written by Albert Fluegel (firstname.lastname@example.org). This manpage was
extracted from the text docs by Christian Meder (email@example.com-