[CentOS] Rsync and differential Backups

[Benjamin Smith]

I did exactly this with ZFS on Linux and cut over 24 hours of backup lag to 
just minutes. 

If you're managing data at scale, ZFS just rocks... 


On Tuesday, November 10, 2015 01:16:28 PM Warren Young wrote:
> On Nov 10, 2015, at 8:46 AM, Gordon Messmer <gordon.messmer at gmail.com> 
wrote:
> > On 11/09/2015 09:22 PM, Arun Khan wrote:
> >> You can use "newer" options of the find command and pass the file list
> > 
> > the process you described is likely to miss files that are modified while
> > "find" runs.
> Well, be fair, rsync can also miss files if files are changing while the
> backup occurs.  Once rsync has passed through a given section of the tree,
> it will not see any subsequent changes.
> 
> If you need guaranteed-complete filesystem-level snapshots, you need to be
> using something at the kernel level that can atomically collect the set of
> modified blocks/files, rather than something that crawls the tree in user
> space.
> 
> On the BSD Now podcast, they recently told a war story about moving one of
> the main FreeBSD servers to a new data center.  rsync was taking 21 hours
> in back-to-back runs purely due to the amount of files on that server,
> which gave plenty of time for files to change since the last run.
> 
> Solution?  ZFS send:
> 
>   http://128bitstudios.com/2010/07/23/fun-with-zfs-send-and-receive/
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