strange dump (dark matter?)

[Ryan Sandridge]

On Oct 22, 2003, at 4:00 PM, Dave McCammon wrote:

>
> --- Ryan Sandridge <ryan at sandridge.org> wrote:
>> Hello all.  I decided it was time to start doing
>> backups.  On Oct 7th,
>> I did a full dump of /usr filesystem (among others),
>> as such:
>> # dump -0uan -f - /usr | gzip -7 >
>> /tmp/20031007-usr-lvl0.dump.gz
>>
>> This seemed to work as expected, here is some info
>> about the gz file:
>> % gzip -l 20031007-usr-lvl0.dump.gz
>> compressed  uncompr. ratio uncompressed_name
>> 507027476 1590855680  68.1% 20031007-usr-lvl0.dump
>>
>> Everything so far so good.  Today (Oct 22) I tried
>> an incremental dump,
>> as such:
>> # dump -5uan -f - /usr | gzip -7 >
>> /tmp/20031022-usr-lvl5.dump.gz
>>
>> Here is where I start getting confused.  While my
>> other incremental
>> backups today (/ and /var), seemed to be fine, the
>> /usr dump was huge.
>> Here is info about the gz file:
>> % gzip -l 20031022-usr-lvl5.dump.gz
>> compressed  uncompr. ratio uncompressed_name
>> 527112624 543600640   3.0% 20031022-usr-lvl5.dump
>>
>> This incremental backup is larger than the original
>> full dump.  Also
>> notice that the compression ratio was 3.0%.  When
>> examining the list of
>> files dumped, I don't see anything that could lead
>> to a file size like
>> this.  A rough count shows that the backup should
>> have been roughly
>> 11MB uncompressed, compared to the 518MB
>> uncompressed.  I've tried
>> reading up on both dump and gzip, but haven't found
>> a clue.  Perhaps
>> I've discovered dark matter.
>>
>> Thanks,
>>    Ryan
>
> Where is the file of your first backup stored?
> Did it get backed up as part of the incremental
> backup?

I should have mentioned that I had checked that already, because that 
would almost explain the unaccounted for 507 MB... but unless I'm 
missing something, that is not the problem.  The backups were made onto 
/tmp filesystem, which were then archived to cd-rom, and deleted from 
/tmp. Ah, might be onto something though... I made an .iso file 
containing the dumps, which was copied to my home directory before 
burning to cd.  That .iso file sat there until today, but was deleted 
before I did today's dump.  So, I suppose it is possible that the 
filesystem wasn't flushed (is that what its called?), so the file was 
still there.  I presume, however, this would be a bug with dump, as 
that .iso file is NOT in the archive.

Do you think this is what happened?

Thanks,
   Ryan