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. rsync is NOT a backup system, its just a incremental file copy with the full/incremental/differential approach, a restore to a given date would need to restore the last full, then the last differential, then any incrementals since that differential, for instance, if you do monthly full, weekly differential and daily incrementals. If you don't use differentials, then you'd have to restore every incremental since that last full, which in a monthly full, daily incremental scenario could be as many as 30 incrementals. -- john r pierce, recycling bits in santa cruz
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..which can be used as a component of a backup system, such as rsnapshot or backuppc.
I beg to differ. The rsync command is a fantastic backup system. It may not meet your needs, but it works really great to make different types of backups for me. I have a script I use (automate everything) to perform nightly backups with rsync. Using rsync with USB external hard drives works far better than any other backup system I have ever tried. As for your other statements, they may be meaningful to you and that is OK, but to me are just so much irrelevant semantics. If one's backup system works, terminology and which commands used to achieve it are beside the point - it is a true backup system. On 11/09/2015 12:59 PM, 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. > > rsync is NOT a backup system, its just a incremental file copy > > > with the full/incremental/differential approach, a restore to a given > date would need to restore the last full, then the last differential, > then any incrementals since that differential, for instance, if you do > monthly full, weekly differential and daily incrementals. If you > don't use differentials, then you'd have to restore every incremental > since that last full, which in a monthly full, daily incremental > scenario could be as many as 30 incrementals. > > > > -- > > > ********************************************************* > David P. Both, RHCE > Millennium Technology Consulting LLC > Raleigh, NC, USA > 919-389-8678 > > dboth at millennium-technology.com > > www.millennium-technology.com > www.databook.bz - Home of the DataBook for Linux > DataBook is a Registered Trademark of David Both > ********************************************************* > This communication may be unlawfully collected and stored by the National > Security Agency (NSA) in secret. The parties to this email do not consent to the > retrieving or storing of this communication and any related metadata, as well as > printing, copying, re-transmitting, disseminating, or otherwise using it. If you > believe you have received this communication in error, please delete it > immediately. >
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 > > ..which can be used as a component of a backup system, such as rsnapshot > or backuppc.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>). And if you aren't familiar with hard links, which rsync happily creates, they were certainly hard enough to wrap my head around, until I got it... and really like them. Just note that they *must* be on one filesystem, as opposed to symlinks, which can cross filesystems. mark