[CentOS] Rsync and differential Backups

Valeri Galtsev wrote:
>
> On Mon, November 9, 2015 12:42 pm, m.roth at 5-cent.us wrote:
>> Gordon Messmer wrote:
>>> On 11/09/2015 09:59 AM, John R Pierce wrote:
>>>> On 11/9/2015 9:50 AM, Gordon Messmer wrote:
>>>>> I don't see the distinction you're making.
>>>>
>>>> a incremental backup copies everything since the last incremental
>>>> a differential copies everything since the last full.
>>>
>>> I guess that makes sense, but in backup systems based on rsync and hard
>>> links (such as rsnapshot), *every* backup on the backup volume is a
>>> "full" backup, so incremental and differential are the same thing.
>>>
>>>> rsync is NOT a backup system, its just a incremental file copy
<snip>
>> Actually, we use rsync for backups. We have a script that creates a new
>> daily directory... and uses hard links to previous dates. That way, it
>> looks like a full b/u... but you can go to a previous date to restore an
>> older version of the file (aka ACK! I saved that file full of garbage to
>> my Great American Novel filename! <g>).
>
> I wonder how filesystem behaves when almost every file has some 400 hard
> links to it. (thinking in terms of a year worth of daily backups).

That, I can't answer - what we have is "disaster recovery", not "archive",
so we only keep them for no more than five weeks.

On the other hand... a reasonable approach would be for, over maybe two
months old, to keep the first of the month, and rm everything else for the
month.

       mark