discrepancies in used space after cpio

[Tim Kientzle]

Paul Wootton wrote:
> 
> I am currently in the process of moving all my data around, going from a 
> single zfs drive (ex-mirror) to a zfs raidz.
> I have used cpio to copy the data to the new pool, but a du shows a big 
> difference in the results.
> 
> Does anyone have any ideas, or does a "du -h ." not do what I think it 
> should?
... <snip> ...
> 
> demophon# pwd
> /DemoPool/var/tmp/kdecache-paul/kpc
> demophon# ls -lah
> total 1282522
> drwx------   2 paul  paul    25B May 15 19:35 .
> drwx------  11 paul  paul    16B May 15 19:36 ..
> -rw-r--r--   1 paul  paul   5.0M May  6 16:47 kapman_cache.data
> -rw-r--r--   1 paul  paul   1.3M May  6 16:47 kapman_cache.index
... <snip> ...
> demophon# du -h .
> 1.2G    .
> 
> demophon# pwd
> /var/tmp/kdecache-paul/kpc
> demophon# ls -lah
> total 7833
> drwx------   2 paul  paul    25B May 18 09:37 .
> drwx------  11 paul  paul    16B May 18 09:12 ..
> -rw-r--r--   1 paul  paul   5.0M May  6 16:47 kapman_cache.data
> -rw-r--r--   1 paul  paul   1.3M May  6 16:47 kapman_cache.index
... <snip> ...
> demophon# du -h .
> 7.6M    .

Dmitry Morozovsky wrote:
 > Ehmm, possibly stupid question: sparse files?

Dmitry's probably right here:  Files .data/.index are
probably some kind of database package, which are
often highly sparse files.

Try "du -k *" in each of these directories to see
how much disk space is actually allocated to each file;
that would verify that file sparseness is at issue here.

Tim