Organizing library

[eschwartz]

Originally Posted by BetterRed

Normal behaviour is that deleting a 'hardlink' (i-node) doesn't delete the 'file' (datastream) unless its the last i-node to the datastream in question.

I'm not sure about e..z's suggested usage of hardlinks and rsynch, maybe he can tell us if there are circumstances that the scripts do delete all the hard links for a given datastream.

BR

Hardlinks point to inodes. The inode is the datastream.

The only ways to delete all hardlinks that point to an inode (at least, all the ways I know of) are to either use something like:
"ls -li" to find the inode and "find -inum $inode | xargs rm" to remove it
or the simpler

find -samefile $file | xargs rm

Either way, yeah. You have to be fairly determined to delete all hardlinks to an inode, because by definition they exist to preserve the datastream unless you specifically delete all locations. If it was acceptable to delete it in one location and break all the other links, we would use soft/symlinks.

Originally Posted by Inferno

Am I mistaken that if I delete the file the link points to it is gone? In the backup as well? or am I missing something?

Hardlinks ensure that if you delete the file, it is still in the other location. Additionally, we do not ever hardlink a backup to your main copy. If we did, then any edits you made would change the inode which is hardlinked from the backup too. That would be bad, since the backup is supposed to show what it used to look like, so... we do not hardlink to the main files, only between the backups themselves.

[Inferno]

So what if I change the file? Is the original file backed up??

[eschwartz]

Originally Posted by Inferno

So what if I change the file? Is the original file backed up??

Yes, even if you change the main file, the backup still contains the pristine original. (Well, the original file from whichever datetime it was backed up.)

[Inferno]

Originally Posted by eschwartz

Yes, even if you change the main file, the backup still contains the pristine original. (Well, the original file from whichever datetime it was backed up.)

Humm. I guess that means something is running to backup the file that "was" a link until I change it.

So if the backup program crashes or is stopped and I change a file then it is gone right?

[eschwartz]

Originally Posted by Inferno

Humm. I guess that means something is running to backup the file that "was" a link until I change it.

So if the backup program crashes or is stopped and I change a file then it is gone right?

There is no constantly running program. There is just a file.

There is one file or set of files, the main ones.

In a second location, a standard file copy creates a backup.
In a third location, a second standard copy is created, but linked to the second location (first copy).

Editing the backup (second or third location) will mess up the other backups regardless of when or why or how.

Editing the main files (first location) will never under any circumstances affect the backup (second or third location).
What it will do, is make any future backups use the new data, and create intra-backup hardlinks only for the identical files.

Hardlinks are a confusing and arcane subject . Perhaps this can clarify them for you?

http://www.mikerubel.org/computers/r...s/#Incremental

Why editing the backups is bad, and how to avoid it.
http://www.mikerubel.org/computers/r...hots/#ReadOnly

[dagdrivaren]

Do you use a custom column for this like the manual shows? Is it preferable? Perhaps even necessary?