UNIX System Administration Handbook - Evi Nemeth [124]
comment "root partitions on reasonably fast machines"
compress client fast
priority low
}
define dumptype nocomp-user {
comment "partitions on slow machines"
compress none
priority medium
}
define dumptype clone-user {
comment "partitions which should only get incrementals"
compress client fast
skip-incr
priority medium
}
define dumptype comp-high-samba {
comment "used for NT filesystems"
program "GNUTAR"
compress server fast
}
define dumptype dos-user {
comment "used for dos partitions that are always mounted"
program "GNUTAR"
compress client fast
}
These particular dump types are all predefined by Amanda. You can use them directly, customize them for your own purposes, or write your own specifications from scratch. The comment field hints at what each dump type does.
The compress parameter specifies where dump data is to be compressed: on the client, on the server, or nowhere. You specify the compression program (e.g., compress or gzip) when you initially install Amanda. The possible values for the compress option are none, client best, client fast, server best, and server fast. The default is client fast.
compress none turns compression off. You might want to choose this option if the server’s tape drive implements compression in hardware. The client options compress the dumps before they are sent over the network to the server, and the server options compress the dumps once they have reached the server’s holding disk. If you want to use software compression, it generally makes more sense to perform the compression on the clients.
The best and fast modifiers tell the compressor how hard to work at squeezing the data; compare with gzip --best and gzip --fast. We only use fast; best can take much longer, and the compression is not significantly better.
The holdingdisk parameter has two possible values: yes and no. It specifies whether the holding disk should be used to spool this backup. You would want to turn this option off when archiving the holding disk itself. The default value is yes.
The maxdumps parameter specifies the maximum number of concurrent dumps that can be run on a client. The default value is 1, but you could increase it for better performance on beefy file servers that have lots of CPU and network bandwidth.
The priority parameter tells how important the backup is. The possible values are low, medium, and high. The default is medium. If there is not enough tape to store all the dumps that have been scheduled, the lower-priority dumps are skipped. In the event of a tape error, Amanda tries to marshall the higher-priority backups onto the holding disk; if there is room, the lower-priority dumps are put there as well.
We recommend defining a different dump type for each priority. Home directories should be dumped at high priority. Medium priority is good for local software packages (e.g., /usr/local), and low priority is appropriate for system files that do not change very often.
The program parameter specifies whether to use dump or gnutar. dump is the default and is usually a better choice.
The skip-full option instructs Amanda to skip the filesystem when a level 0 dump is due. You would generally select this option when level 0 dumps are performed outside of Amanda. For example, you might choose to do level 0s only when the machine is in single-user mode.
The skip-incr option makes Amanda skip all dumps except level 0s. You’d choose this option for archive configurations in which only full dumps are done and the tapes are saved indefinitely.
The disklist file
The amanda.conf file tells how to do dumps without actually specifying any clients or filesystems to dump. That information is recorded in the disklist file. Each client filesystem is assigned one of the dump types defined in amanda.conf.
##############################################################
# client partition dumptype # mountpoint
##############################################################
# the dump server
ocean sd0a comp-root # /
ocean sd0g comp-user # /usr
ocean sd0d