OpenSource backup Solution: Amanda Netbackup
Amanda is the Advanced Maryland Automatic Network Disk Archiver, developed at the University of Maryland in the 1990s. While it is now maintained at SourceForge and support is provided only through mailing lists and a FAQ-O-MATIC, it is still a highly useful, stable network backup utility with a wide range of features. Amanda is tailored for networks that have a central server with a high-capacity tape drive and multiple backup clients. Although Amanda was built for UNIX systems, it has been extended to provide backup services to Windows clients (via Samba, although a separate project is underway to develop a native Windows client) to allow deployment in heterogeneous environments.
Architecture
Amanda is a client-server application where the server pulls backups from individual clients according to specifications defined in a named configuration. Amanda can pull multiple streams from different clients at the same time, writing each stream to a file on a designated “holding disk” on the tape server, copying the files to the tapes one at a time. This provides an efficient use of network resources and limits the backup window requirements for the clients while reducing the complexity of the backup database. Amanda comes with support for two different archiving utilities, gnutar and dump, but support for additional archiving utilities can be added by modifying the client source code. Amanda originally was designed with the use of dump as its primary choice of archiving utility, but because of synchronization issues with running dump on live filesystems, most users of Amanda recommend using gnutar as the archiving software.
Amanda’s unique advantage over other backup systems is that it manages a schedule of full and incremental backups according to a strategy that attempts to keep the amount of tape required for an individual run to a minimum while ensuring that restoration can be done with the fewest possible tapes. Where other backup systems, including most commercial systems, require an explicit incremental/differential/full backup, Amanda develops its own schedule and modifies it according to the conditions of the most recent backups. This capability makes attempts to explicitly force Amanda into following a preset schedule difficult and fraught with pitfalls.
Architecture
Amanda is a client-server application where the server pulls backups from individual clients according to specifications defined in a named configuration. Amanda can pull multiple streams from different clients at the same time, writing each stream to a file on a designated “holding disk” on the tape server, copying the files to the tapes one at a time. This provides an efficient use of network resources and limits the backup window requirements for the clients while reducing the complexity of the backup database. Amanda comes with support for two different archiving utilities, gnutar and dump, but support for additional archiving utilities can be added by modifying the client source code. Amanda originally was designed with the use of dump as its primary choice of archiving utility, but because of synchronization issues with running dump on live filesystems, most users of Amanda recommend using gnutar as the archiving software.
Amanda’s unique advantage over other backup systems is that it manages a schedule of full and incremental backups according to a strategy that attempts to keep the amount of tape required for an individual run to a minimum while ensuring that restoration can be done with the fewest possible tapes. Where other backup systems, including most commercial systems, require an explicit incremental/differential/full backup, Amanda develops its own schedule and modifies it according to the conditions of the most recent backups. This capability makes attempts to explicitly force Amanda into following a preset schedule difficult and fraught with pitfalls.
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