Re: Hard link / rsync backup strategy successful

Kevin,

Kevin Grittner wrote:
> As a follow-up to this:
>
> http://archives.postgresql.org/pgsql-admin/2009-03/msg00233.php
>
I just read this post.  What exactly does doing the hard link buy you
here?  Since it's just another inode pointer to the same file, I fail to
see what the purpose of it is...  For example, take a look at the code
below :

chander@bender:~$ echo "apple" > a
chander@bender:~$ cat a
apple
chander@bender:~$ cp -l a b
chander@bender:~$ cat b
apple
chander@bender:~$ echo "pear" > a
chander@bender:~$ cat b
pear

Just curious...  It seems that the method described in your email
(creating a backup using 'cp -l' and then using rsync) would "break"
your old backup (the hard link copy) since some of the files in it would
be modified, but it would be missing the "new" files that were added to
the backup.  Essentially making your "old" backup an incomplete backup
of your new cluster.

In essence, a "hard link" isn't a copy of any sort, it's just a pointer
to the same inode, which is the exact same data...

Perhaps there is something that I am missing here?

Thanks

--
Chander Ganesan
Open Technology Group, Inc.
One Copley Parkway, Suite 210
Morrisville, NC  27560
919-463-0999/877-258-8987
http://www.otg-nc.com
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