[CentOS] Rsync and differential Backups

Sat Nov 14 20:12:19 UTC 2015
Gordon Messmer <gordon.messmer at gmail.com>

On 11/14/2015 09:01 AM, Mark Milhollan wrote:
> On Fri, 13 Nov 2015, Gordon Messmer wrote:
>> Breaking a RAID volume doesn't make filesystems consistent,
> While using LVM arranges for some filesystems to be consistent (it is
> not always possible)

Can you explain what you mean?  The standard filesytems, ext4 and XFS, 
both will be made consistent when making an LVM snapshot.

> , it does nothing to ensure application consistency
> which can be just as important.  Linux doesn't have a widely deployed
> analog to Windows' VSS, which provides both though only for those that
> cooperate.

I know.  That's why I wrote snapshot:

> On Linux you must arrange to quiesce applications yourself,
> which is seldom possible.

I have not found that to be true.  Examples?

>> Breaking the
>> RAID will duplicate UUIDs of filesystems and the name of volume groups.
> Making an LVM snapshot duplicates UUIDs (and LABELs) too, the whole LV
> is the same in the snapshot as it was in the source.

The VG name is the bigger problem.  If you tried to activate the VG in 
the broken RAID1 component, Very Bad Things(TM) would happen.