[TriLUG] Anyone using rdiff-backup?

[William Sutton via TriLUG]

NetBackup refers to this as a synthetic full backup.

William Sutton

On Sat, 25 Feb 2023, Steve Litt via TriLUG wrote:

>>>>> What are reverse differential backups?
>>>
>
> Brian Bouterse said on Sat, 25 Feb 2023 09:25:29 -0500
>
>> It's a differential backup so each backup can be restored as a point in
>> time snapshot but it minimizes storage by only storing the diffs in
>> between each one. Typically with regular differential backups the full
>> copy is kept as the first backup and all subsequent back ups are
>> diffs. With a reverse differential the latest backup is always the
>> full copy.
>>
>> What's really nice about that is the latest backup is usually much more
>> useful than the first backup. By being stored in this way you don't
>> need any reassembly to access the latest backup files.
>
> Thanks Brian, I understand now.
>
> I achieve reverse differential backups by doing a cp -al after the
> rsync. Here's my script:
>
> =================================================
> [slitt at mydesk backup_local]$ cat make_incremental.sh 
> #!/bin/bash
> [ -d /mnt/backup_local/stevebup/latest/meta ] || exit 11
> datestamp=`head -n1 /mnt/backup_local/stevebup/latest/meta/timestamp.txt`
> incname=inc_$datestamp
>
> cd  /mnt/backup_local/stevebup
> echo "PLEASE WAIT, MAKING INCREMENTAL COPY, cp -al latest $incname..."
> time cp -al latest  $incname
> echo "DONE WITH    MAKING INCREMENTAL COPY, cp -al latest $incname..."
>
> [slitt at mydesk backup_local]$ 
> =================================================
>
> SteveT
>
> Steve Litt 
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