Re: incremental backups howto?
Joao Clemente wrote:
> In the latest thread about "Synchronize two servers" it was
> talked about incremental backups. Well, can you quick-start me
> in this topic?
An incremental backup is done by backing up all files that have changed
since the last full or incremental backup. How this file list is tracked
depends on the backup program used (some might use a filesystem flag,
others might use modification timestamps).
The downside of incremental backups is that, to do a full restore, you need
the last full backup and ALL the incremental backups since the last full.
A better alternative is a differential backup, which is all files that have
changed since the last full backup. This is much easier to restore, because
all you need is the last full backup and the last differential backup.
> What do you say?
Another interesting approach is that taken by tools such as dirvish or
rsnapshot. Both of these tools use rsync to capture snapshots of a
filesystem (either local or remote) to disk. Within the backup archives,
files that have not changed between snapshots are hard linked.
This gives the completeness and ease of restoration of full backups without
requiring nearly as much space to store data. To restore, just copy back
the desired snapshot.
This is all for general filesystem backup. For databases, check the
documentation to see what the recommended backup method is.
Adam
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