Backups with AMANDA

Restore Files From Amanda

Background

We have two main file-servers (musashi, and yamato), which each perform their own backups Monday through Friday (typically). Musashi has a SCSI-attached HP LTO-1 Ultrium 230 (Aug. 2003) tape-drive; yamato has a replacement Ultrium 232 (Nov. 2006) tape-drive.

Yamato only backs up it's SCSI-connected RAID drives. Musashi doesn't back up one of it's own SCSI-connected RAID drives (too much non-essential data), but musashi does "reach out" and backup other machines' files. What gets backed up is listed/controlled in the /etc/amanda/Dailyxxx/disklist. Both yamato and musashi have amanda configured as a server and client, while the remote machines captured by musashi have amanda configured as a client-only.

Amanda Server Configuration

The first step was to determine the tapetype entry, in /etc/amanda/Dailyxxx/amanda.conf; here are the results from two different tests on separate systems:

Ultrium 230

define tapetype Ultrium230 {
    comment "HP Ultrium 230, produced by amtapetype"
    length 101376 mbytes
    filemark 0 kbytes
    speed 13871 kps
}

Ultrium 232

amanda@trainwreck ~ $ amtapetype -f /dev/nst0 -e 100G -o
Writing 1024 Mbyte   compresseable data:  37 sec
Writing 1024 Mbyte uncompresseable data:  72 sec
WARNING: Tape drive has hardware compression enabled
Estimated time to write 2 * 102400 Mbyte: 14400 sec = 4 h 0 min
wrote 3080192 32Kb blocks in 94 files in 7025 seconds (short write)
wrote 3096576 32Kb blocks in 189 files in 7511 seconds (short write)
define tapetype unknown-tapetype {
    comment "just produced by tapetype prog (hardware compression on)"
    length 96512 mbytes
    filemark 0 kbytes
    speed 13611 kps
}

Tape Drive Compression

Compression can be turned on or off using the mt tool noted below, then initiating the tapetype check; kill the tapetype check with ctrl-C when you've got enough info (takes quite a few minutes)

trainwreck ~ # mt -f /dev/nst0 defcompression 1
trainwreck ~ # su - amanda
amanda@trainwreck ~ $ amtapetype -f /dev/nst0 -e 100G -o
Writing 1024 Mbyte   compresseable data:  42 sec
Writing 1024 Mbyte uncompresseable data:  72 sec
WARNING: Tape drive has hardware compression enabled
Estimated time to write 2 * 102400 Mbyte: 14400 sec = 4 h 0 min

amanda@trainwreck ~ $ logout
trainwreck ~ # mt -f /dev/nst0 defcompression 0
trainwreck ~ # su - amanda
amanda@trainwreck ~ $ amtapetype -f /dev/nst0 -e 100G -o
Writing 512 Mbyte   compresseable data:  38 sec
Writing 512 Mbyte uncompresseable data:  39 sec
Estimated time to write 2 * 102400 Mbyte: 15600 sec = 4 h 20 min