incremental backups howto?
Hi people. In the latest thread about "Synchronize two servers" it was
talked about incremental backups. Well, can you quick-start me in this
topic?
I have the notion of what an incremental backup is... it would be
keeping the "delta" from the last state, but how is this done in
practice? Is it done with "tar" with some flag? Can we compress the
backups (tar.[gz|bz2]) or it needs to be uncompressed to create the
"delta"? Can we do a "2nd_delta" from a "backup + 1rst_delta"? Or the
"2nd_delta" is created directly from "backup" therefore overriding the
need for the "1rst_delta"?
Maybe its not even done with "tar"... I keep thinking on "diff's" and
"patch's" but maybe its not the same here.
If one needs the (uncompressed) initial tar available from a backup to
find the "delta", this means we need a "2xN" disk, where "N" is the info
we have in disk.. so you could only do incremental backups in a disk
with less than 50% occupation.. rigth or wrong?
What do you say? Pointer to right commands/howto's? Thanks
Joao Clemente
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