Backup server (old)

amanda.conf

• dumptypes
• dumpcycle
• estimate timeouts
• Tapetype definitions

Exclude lists

This part has been moved to a separate page. See Exclude and include lists.

Device configuration

Tapetypes

Tapetype definitions are specified in amanda.conf configuration file. The tapetype definition provides AMANDA how much it is supposed to be able to store in a tape (length), how much space is wasted at the end of a dump image with the EOF mark (filemark) and how fast the tape unit is (speed).

The most important parameter is length, since AMANDA may decide to delay a backup if length is too small, but, if it is too large, AMANDA may end up leaving dumps in the holding disk or having to abort some dump.

Filemark is important if you have many disks, particularly with small incremental backups. The space wasted by so many filemarks may add up and considerably modify the available tape space.

The speed is currently unused.

AMANDA provides the amtapetype utility to calculate the size of a tape, to generate a "tapetype" entry for your amanda.conf.

Specifying the appropriate tape device, but beware that it may take many hours to run (it fills the tape twice ...). Make sure you do not use hardware compression, even if you plan to use hardware compression in the future. amtapetype writes random data to tape, and random data will expand instead of compressing, therefore you'll get an estimate that's smaller than expected.

Some tapetype definitions are available here.

Changers

This part has been moved to a separate page.

See Changers.

RAIT

Currently it is only integrated with the chg-manual changer script

RAIT is an acronym for "Redundant Array of Inexpensive Tapes", where data is striped over several tape drives, with one drive writing an exclusive-or-sum of the others which can be used for error recovery. Any one of the data streams can be lost, and the data can still be recovered.

This means that a 3-drive RAIT set will write 2 "data" streams and one "parity" stream, and give you twice the capacity, twice the throughput, and the square of the failure rate (i.e. a 1/100 failure rate becomes 1/10,000, since a double-tape failure is required to lose data).

Similarly, a 5-drive RAIT set will give you 4 times the capacity, 4 times the throughput (with sufficient bus bandwidth), and the square of the failure rate.

This means you can back up partitions as large as four times your tape size with AMANDA, with higher reliability and speed.

Using a RAIT

This section has been moved to a separate section.

See: Rait.

Disaster Recovery

To assist in disaster recovery (as well as changer scripts) the AMANDA package now also includes amdd, which is a simple dd(1) replacement which supports (only) the "if=xxx", "of=xxx", "bs=nnn[kMb]" "skip=nnn" and "count=nnn" options, but which can read and write RAIT tapesets.

Using amdd and your usual AMANDA unpack instructions will suffice for disaster recovery from RAIT tape-sets.

File driver/Disk backups

This section has been moved to a separate page;

See File driver.

Server-side and Client-side encryption

This section has been moved to a separate page.

See Encryption.

Custom Compression

• compress client custom
  • Specify client_custom_compress "PROG"
  • PROG must not contain white space and it must accept -d for uncompress.

• compress server custom
  • Specify server_custom_compress "PROG"
  • PROG must not contain white space and it must accept -d for uncompress.

• sample dumptype:

 define dumptype custom-tar {
 global
 program "GNUTAR"
 comment "root partitions dumped with custom compression"
 compress server custom
 server_custom_compress "/usr/bin/my_gzip"
 priority low
}

• I have tested custom compression using bzip2. Dumps works fine. Amrestore has a glitch on which

the image gets uncompressed correctly and written to a temp file but gets a broken-pipe error. I am investigating the problem.

Tape hardware compression

There are multiple methods to set (turn off) hardware compression.

• Using stinit command: stinit(8) command initializes the SCSI tape drives at the system startup by sending driver ioctl commands. Use "comp" field in /etc/stinit.def configuration file to configure hardware compression for each type of tape.

• Use mt(1) command to turn off hardware compression at boot time. For example:

# mt -f /dev/st0 compression 0

Please note that compression information is not stored on the tapes ident header block until the tape has been written to.

Procedure for turning off compression and labelling tapes

• Label the tape
• Rewind the tape
• Read the label to a file using dd command
• Turn off tape compression using mt(1) command. See above.
• Re-write the label block and write more /dev/zero blocks to flush its buffers.