Rsync --link-dest and ext3: can I increase the number of inodes?

Cameron Simpson cs at
Mon Sep 22 04:12:57 UTC 2008

On 21Sep2008 22:27, Theodore Tso <tytso at> wrote:
| On Sun, Sep 21, 2008 at 08:44:57PM -0400, Richard Michael wrote:
| > (I run rsync --link-dest backups onto ext3 and am anticipating running
| > out of inodes.) [...]

Hmm. While I take the point that each link tree consumes inodes for the
directories, in a tree that changes little the use of new inodes for
new/changed files should be quite slow.

[...snip e2fsck memory requirements...]
| Alternatively, you could try using a backup program which uses a real
| database to keep track of reused files, instead of trying to use
| directory inodes and hard links as a bad substitute for the same.

But a database is... more complicated and then requires special db-aware
tools for a real recover. The hard link thing is very simple and very
direct. It has its drawbacks (chmod/chown history being the main one
that comes to my mind) but for many scenarios it works quite well.

For Richard's benefit, I can report that I've used the hard link backup
tree approach extensively on ext3 filesystems made with default mke2fs
options (i.e. no special inode count size) and have never run out of
inodes. Have you actually done some figuring to decide that running out
of inodes is probable?

Cameron Simpson <cs at> DoD#743

Peeve:  Going to our favorite breakfast place, only to find that they were
        hit by a car...AND WE MISSED IT.
                - Don Baldwin, <donb at>

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