|
Re: [Networker] Hard links
2005-02-15 09:57:51
Charles Gruener wrote:
Thanks for the reply, Jason.
To quote the GNU tar manual, Section 8.6, "tar's way of handling multiple
hard links to a file places only one copy of the link on the tape, but the
name attached to that copy is the only one you can use to retrieve the file;
cpio's way puts one copy for every link, but you can retrieve it using any
of the names."
It seems to me that hard links are definitely supported in two other basic
backup programs. This is why I am surprised that NetWorker does not go to
the filesystem level. I guess I'll have to investigate other options for a
NetWorker backup of my ext3 hard linked rsync backups.
I had to think about this for a while before I understood what you
meant. From your explanation neither tar or cpio seem to be handling
this very well, but from a test I have just run, NetWorker seems to
behave correctly. NetWorker of course has the benefit of a sophisticated
index database that tar and cpio don't have.
My test was to copy a file of just over 2MB to a directory, then create
10 more hard links to this file. I backed up the directory, and the
resulting save set was just over 2MB. So it hasn't backed it up 11
times, just once, plus perhaps a small overhead for the extra hard
links. I then deleted all the files and restored them from the backup.
They were correctly restored as a single file, with 11 inodes - verified
by "ls -li" to have the same inode number.
So I believe you are mistaken about your backups being 90% larger,
unless it it simply from the fact that your files are very small and
there are a very large number of inodes.
What I don't quite understand is what you are trying to accomplish with
rsync in this case. Perhaps you would like to explain further then
possibly we can offer more advice?
--
Note: To sign off this list, send a "signoff networker" command via email
to listserv AT listserv.temple DOT edu or visit the list's Web site at
http://listserv.temple.edu/archives/networker.html where you can
also view and post messages to the list. Questions regarding this list
should be sent to stan AT temple DOT edu
=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
|
|
|
