Re: Homebuilt NAS Advice
On 8/6/2020 9:07 AM, Celejar wrote:
On Thu, 6 Aug 2020 05:02:17 -0500
Leslie Rhorer <lesrhorer@att.net> wrote:
* Incremental and differential backups are backups of the delta between
the last full backup and the current system state (either individually
[differential] or collectively [incremental])
* I have no idea (nor do Google, DuckDuckGo, or Wikipedia) what a
"decremental backup" is.
I suggest reading the DAR features list. I will post it again:
http://dar.linux.free.fr/doc/Features.html
Meanwhile, a decremental backup is defines as:
As opposed to incremental backups, where the older one is a full backup
and each subsequent backup contains only the changes from the previous
backup, decremental backup let the full backup be the more recent while
the older ones only contain changes compared to the just more recent
one. This has the advantage of providing a single archive to use to
restore a whole system in its latest known state, while reducing the
overall amount of data to retain older versions of files (same amount
required as with differential backup). It has also the advantage to not
have to keep several set of backup as you just need to delete the oldest
backup when you need storage space. However it has the default to
require at each new cycle the creation of a full backup, then the
transformation of the previous full backup into a so-called decremental
backup. Yes, everything has a cost!
* Borg doesn't fit the "full / differential / incremental" paradigm
neatly, but it certainly has some of the advantages of differential /
incremental backups (plus others that classic differential /
incremental ones do not have, such as deduplication - i.e., if the
backup source contains multiple copies of some data, that dataonly
needs to be stored once in the backup target).
And how useful is that? There are very few duplicate files on my
systems, because I use applications to eliminate duplicates.
Eliminating duplicates in a live data repository is far more important
than doing it on backup media.
* I don't know exactly what you mean by "deletion restoral", but Borg
(and, I assume, many other good backup solutions) offers a
flexible variety of methods to restore deleted files
No. It is the opposite of that. It is the option to not restore files
that have been deleted since the backup, or to actively delete files
during a restore. It is similar - but not the same as - directing the
restore not to restore files that do not exist on the restore target.
, and / or to
restore a snapshot of the backup source as it existed at a given point
in time: https://docs.borgbase.com/restore/
If you are willing to explain further, that would be appreciated.
Thanks!
Celejar
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