[Techtalk] my home directory grew

[Daniel Pittman]

Maria McKinley <maria at shadlen.org> writes:
> Chris Wilson wrote:
>> On Tue, 21 Apr 2009, Maria McKinley wrote:
>> 
>>> I recently moved our home directories from a hard drive to a RAID array.
>>> Initially I copied the home directory like this:
>>>
>>> nohup cp -a /home/* /new_home/ &
>>>
>>> Then, once it was done, I disconnected the machine from the network, so
>>> no one could mess with the home directories, and used rsync:
>>>
>>> rsync -av /home/ /new_home
>>>
>>> For some reason after I was done copying, the home directories had grown
>>> from 539G to 907G. There are no strange new directories, and it appears
>>> that links have been preserved correctly. Anybody have any ideas what
>>> could have happened?
>>
>> Do you mean it grew on the destination system between immediately
>> before the rsync and immediately after? I that case I would guess
>> that somebody added 360G of files in the mean time, or has been using
>> sparse files.
>>
>> Or do you mean that it was 540G on the old system and 907G on the
>> new?  In that case I'd guess a difference in filesystem or in cluster
>> size of the filesystem.
>
> The latter. 540G on the old system, 907G on the new. That is over
> 350G.  Crazy. Glad the new RAID array is large...

I can think of two possibilities before getting into the realms of
strangeness.

One is that rsync is very ... exciting in the interpretation of what it
should do when a trailing slash is or isn't present, and I usually
manage to get it wrong and create a second copy of a directory tree once
every few months or so.

I presume you checked that, though, so the other possibility that
springs to mind is that they are on a different filesystem, and that you
have either lost tail-packing on ReiserFS[1] or gone from a 1K block
size to a 4K block size — and have an awful lot of small files.

Regards,
        Daniel

Footnotes: 
[1]  ...which is, overall, probably a win.