Re: Hard link / rsync backup strategy successful

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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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