Hi Joe, If you want to understand hard-links, just take a look at Wikipedia : http://en.wikipedia.org/wiki/Hard_link#Example
I think it's pretty easy to understand. To understand how hard-links (and rsync) can help you make strong incremental backups, head over http://blog.interlinked.org/tutorials/rsync_time_machine.html Cheers, -- François Le mardi 22 janvier 2013 23:12:38, Joe a écrit : > Thanks for the reply. I know what hard and soft links are and have some > idea of how they relate to backup. > > What I need is a tutorial on how all of that works with rsync. I can > see that there are a lot of considerations as to which options to use > for different situations and maybe some general strategies on how to > build something like an incremental or differential backup. > > I use rsync now on a one directory tree to one directory tree basis now, > but I'd like to have more than one backup on my backup device without > doubling the storage which is what hard links will help me do once I > know how they work in more detail. > > Joe > > On 01/22/2013 02:48 AM, Tony Abernethy wrote: > > This may help: (man ln) > > > > A hard link to a file is > > indistinguishable from the original directory entry; any changes to a > > file are effectively independent of the name used to reference the file. > > Hard links may not normally refer to directories and may not span file > > systems. > > > > Assuming you do many backups and many of the files do not change, > > hard links are your friend. > > > > Backing up soft links: > > Do you back up the link or what the link points to? > > (Even that simple thing has interesting ways to get complicated.) > > > > -----Original Message----- > > From: [email protected] > > [mailto:[email protected]] On Behalf Of Joe Sent: Tuesday, > > January 22, 2013 1:32 AM > > To: [email protected] > > Subject: Is there a howto/tutorial on backups/rsync that covers the use > > of hard and soft links? > > > > There have been a lot of posts on the list lately about issues with hard > > links. It has been very interesting, but I don't understand it very > > thoroughly. I haven't used hard links for anything yet. I've used > > symlinks - not for backups, of course - and have seen them get broken or > > deleted in backups. > > > > Is there a tutorial anywhere that will explain how this works (assuming > > that the reader understands the basic concepts of backups and knows how > > to program, but doesn't really understand how to use links to create > > things like incremental or differential backups)? It seems like there > > are a lot of fine points to consider, some of which can really bite you > > if you don't take them into account. > > > > I'm working on my own personal backup system using bash and rsync. When > > it's done it will be pretty good, but it would be *much* better if I > > rewrote it to have more backup versions using hard links to save space. > > > > I am writing my own because (aside from learning a lot) I have only seen > > two types of backup utilities - those that are very simplistic and won't > > let me do what I want and those which are enterprise level and I can't > > figure out how to get them to do anything without extensive study. (I > > did experiment with areca (I think it uses rsync libraries under the > > hood) which would probably do everything I want, but I got stuck too > > many times and couldn't get enough support on their forum to keep > > going.) > > > > TIA > > > > Joe > > > > -- > > Please use reply-all for most replies to avoid omitting the mailing list. > > To unsubscribe or change options: > > https://lists.samba.org/mailman/listinfo/rsync Before posting, read: > > http://www.catb.org/~esr/faqs/smart-questions.html -- Please use reply-all for most replies to avoid omitting the mailing list. To unsubscribe or change options: https://lists.samba.org/mailman/listinfo/rsync Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html
